Windows Down, Up, Heat, or A/C? Best Gas Mileage

[@Takenzo75]

You forgot windows down and AC on full! ... just kidding.

[@monad_tcp]

Actually, he forgot windows up with AC on full, and to question if it does damage the AC doing that or not.

[@Guitarfollower22]

This guy is the man. I wish he taught a course at my college, I'd be happy to go everyday :)

[@lazerbeastgamer355hd7]

That spider scared me

[@mohammedmustafa2370]

@@lazerbeastgamer355hd7 me too

[@balraj25997]

@@lazerbeastgamer355hd7 me too

[@HambertHM]

Nice test! Personally I just use whatever I need to feel comfortable and don't worry about the little gas mileage i'm loosing. I think feeling OK when driving is key for safety and to eliminate fatigue. The only time I worry about my vehicle's efficiency is when it's time to buy a new one! (general fuel economy, not just temporal shifts like when using the AC).

[@mainmain5303]

Wind speed and direction?

[@jackson5116]

or the aerodynamics of the vehicle. A passenger car is less aerodynamic than a sports car.

[@MegaDmayo]

Man i watched all your project integra vids! You should do more installation and performance testing videos! I love how you explain everything so well!

[@EngineeringExplained]

MegaDmayo Glad you enjoy them, thanks for watching!

[@adamboursalian5355]

Your editing is improving. Few new fonts, some gfx, the shirts a nice touch =D You do deliver sir; and nobody discredited or lost trust in you for forgetting a control in ONE experiment; espeically since you immediatetly recognized and fixed the problem; and improved the report. More than we expect from fortune 500s =D Give yourself a pat on the back. Too many smart kids dont give themselves credit;

[@quincyadams6961]

Haha as soon as I saw your speedometer I knew it was an integra. I've had in for 2 years now, you are officially the man #INTEGRAUNITED ✊👌

[@MessiahNerves]

i dont think i know a single person that would even want the windows down at 60+ miles.

[@EngineeringExplained]

MessiahNerves Haha very true.

[@FerpiliciousProducts]

I live in a place where you can only have windows down 2-3 months a year so I rock my windows down at any speed in the summer haha.

[@CapnFlappyJaw42]

+MessiahNerves Well, there was one time I was a complete idiot and got high off my ass before driving 3 hours to my friends house in the City, and having the window down, with the cold wind blowing at my face while going 65-70 mph was the only thing keeping me semi-sober for the first 2 hours of the trip. ...Never again will I do that.

[@sminem6572]

My dad loves his windows down at 75

[@jeffgendron1959]

+MessiahNerves That's what I thought, most people will naturally adjust the windows to be much less open when they merge onto a highway. I do that without even thinking about it. I've just seen the Mythbusters video on this subject and they claim the windows open are worse than the A/C!

[@Wheelin_Dealin]

I like your videos but feel as though there is too many external variables acting on your way or testing... I've read below you did take this on the same day as the old data, so that's good but... Was the runs all done at exactly the same spot? Any differing in slope or angle could cause bad data. How much fuel was burnt in between the first and last run? Weight would play a factor and if you were starting at the same point on the highway everytime I'm sure looping back around to the spot ya burnt a gallon or so... Was the A/C compressor clutch engaged on the start of the runs? The system cycles on and off so the draw could effect acceleration depending on what part of the cycle it was on. Change of weather or wind/gusts during testing. Engine temp and efficienty of the engine at time of runs. Think of dyno runs and how each run is never the exact same. There are always slightly different due to efficienty and/or temp etc I like the myth that's being tested but i don't think this is the best environment to do so.

[@EngineeringExplained]

Same spot, alternating runs (so fuel weight wouldn't be a concern), engine at operating temp, all of the runs within about an hour so outside conditions remained relatively stable. A/C started at the start of the A/C runs.

[@0thomas0thomas]

Engineering Explained It's kind of inconsistent to analyze differences around 1% when what you read on your speedometer is clearly not 1% accurate...

[@jakubkrcma]

Thomas Fernandez You would be surprised, but speedometer readings are VERY consistent, easily within 1 %. They are not accurate concerning *actual speed*, of course, because that depends on the specific conditions (tire size, pressure, wear, car weight, etc.), but I used to measure real-world performance and fuel consumption for some time and one of the things we did was 3rd gear SPEEDOMETER 40-120 km/h (~25-75 mph) acceleration (to determine the power effect of some engine enhancements). In 5 consecutive runs, a Mazda showed e.g. 16.00 s 4 times and 16.04 s 1 time (back in 2005, we only had a 25fps digital video camera). That's 5 runs within 0.25%! (I don't remember the actual figures, but 4 times were *identical* (within 40 milliseconds) and 1 time was a neighbouring video frame. It could be 4x 16.08 and 1x 16.04, for example.) We were QUITE shocked by the repeatability of that test. And it was done on a regular road (same starting spot, same direction, all 5 runs done in 5 minutes, calm air). I have encountered only ONE case of insufficient consistency. But that was in a car with a cracked hose, which feeds air to the intake manifold.

[@sharedknowledge6640]

Nice explanation although it would be best done in very warm temps (unlikely this time of year in western Oregon) to prevent the A/C compressor from cycling off to prevent the evaporator from freezing. Even with "MAX A/C" enabled the compressor will cycle on and off in most cars unless the air over the evaporator remains at about 85 or higher degrees F. Also, this has probably been covered, but many cars shut the A/C off at wide open throttle (WOT) for better performance. I'm surprised your Subaru doesn't? It's done to provide better performance as few cars are driven at WOT for any length of time and you don't really miss the loss of cooling. So that would seriously mess up doing a timed WOT pull comparison as the A/C would be off in both cases. But your conclusion is still correct and has been documented elsewhere--windows down is better at low speeds and windows up is better at high speeds. And for your Integra you also have to factor in the weight savings if you remove the A/C hardware.

[@mastersimonsays]

What about doing full heat in the winter? This also gets me wondering what if you had different levels of A/C, heat, and windows down.

[@GMWsho]

A possible reason for very small changes in windows up and down could be down to the aerodynamics of the car and how much air is actually being disturbed causing drag. Each car has different amounts of air passing the windows and in some cases it might not have a huge difference but it still baffling that there is only a small difference. (you might have said this I haven't watched whole video yet). Love the experiment.

[@brandonabuan2238]

When you say "heat on full", are you including your fans to blow on full as well?

[@EngineeringExplained]

brandon abuan Yes.

[@Pringlulz]

This is some good analysis, like in all of your videos, but could I make a suggestion for future tests like this? I'm currently in my third year undergraduate engineering program at the moment, and I don't know if it was a mandatory course for yours but I've taken a Statistics for Scientists course, and applying those methods to sets of data like this can help a lot with ruling out whether a test is valid or not. The control group is an obvious omission, but you can also look at how your data fits onto a normal curve and the distribution of data to see whether those small variations are statistically significant. Of course, it's also hard to draw conclusions from such small data sets anyways, but a few simple equations can help dramatically with your analysis. Loving these videos, and by the way, is there a possibility of being able to buy those shirts as merch?

[@mackdaddie80]

The Integra cpu changes its ignition timming at 3500 rpm for more performance in the higher revs of the engine. Im not speaking about vtec in a Gsr trim Integra. It appears you have a B18 non vtec engine in an LS or RS trimmed Integra. This may help.

[@nambinhvu]

What about slightly open, half open, front open more than back, back open more than front, etc.?

[@benjaminweatherford8069]

What i would do to test fuel efficiency in these different scenarios is put x amount of gas in the tank and run around a closed circuit with the cruise control on. This eliminates as much of the human error as you can. The issue I have with your test is with the acceleration. This is testing the amount of power loss more than the fuel economy. While they are related, I don't agree it's the most suitable way to test fuel economy.

[@marcusmizerak]

If your car starts to run hot out of nowhere is it better to run heat full blast or put AC on or pop hood a crack for added air flow in an emergency?

[@johnnieburkhalter5265]

This MIGHT make my sister run the A/C in her car. Since she runs with windows only. On the FULL heater test, was the compressor on or off? My car runs the compressor regardless of temp setting.

[@WelshyAutomotive]

Can you explain why car squat when launching from a dig? Why the suspension drops fast.

[@johnbarron4265]

The ground pushes forward on wheels of the car, producing a nose-up pitching moment. The car pitches nose-up until the coil springs deflect enough to produce a nose-down pitching moment to counter the ground-induced pitching moment. The faster the car accelerates, the more its pitch attitude changes. The stiffer the spring rates, the less the pitch attitude will change, and the quicker the car will reach its nose-up pitch attitude.

[@John76222]

I now know the music engineering explained listens to when driving

[@seb5945]

Music in Engineering Explained video, huh? First time, I think.

[@tonyhull9427]

Why does the left turn signal come on at 3500 rpm? 🤔

[@monkey314159]

Why is the A/C on full? Shouldn't the A/C be set to a comfortable temperature? Nobody blasts the A/C when they're freezing.

[@Papercleeep]

in your older videos, you look like george harrisson man anyway, good videos! addictin

[@juris822]

Please do the video on Flow Cell technology in cars

[@karimjundi2941]

Hey, I asked this question in the last video and never got an answer, its of topic, but why do you turn your left blinker on right before 60 mph? Are you merging onto the highway or something?

[@EngineeringExplained]

Visual stimulation, makes the video quite exciting. Or maybe your theory. :)

[@karimjundi2941]

Lol, not sure what all that means, but awesome video regardless. Also really enjoyed the differential videos took me forever to figure out the Torsen video. Thanks

[@TheSoab117]

What do you do for a living Engineering Explained

[@hgmailcom]

He has a job as a Mechanical Engineer I think, I'm pretty sure KZbin is a part time thing as well

[@deadguy237]

SOMETHING TO KEEP IN MIND IS THAT MOST NEW CARS 95 AND NEWER. MOST. WILL RUN AC COMPRESSER WHEN HEET IS ON.

[@EngineeringExplained]

No, just fans over a heater core.

[@DENicholsAutoBravado]

Only if defrosting windows.

[@deadguy237]

DE Nichols my car any heat runs it :(

[@DENicholsAutoBravado]

Oi ve. What a waist of gas.

[@deadguy237]

yep no heat for me

[@AaronShenghao]

... AC is there for a reason... USE IT

[@vanhakaveri]

Windows down is worse than air conditioning for multiple reasons. It does not cool You except if it is cold outside and you get wind noise.

[@OhPoWneDiel]

i does coool you, just like a fan will cool you even though its blowing the same air at the same ambient temperature that you felt hot

[@cobraa340]

It does cool you. Besides, having straight pipes and the windows rolled down is heaven.

[@icekk007]

When you are accelerating WOT, the largest load is inertia force (F=ma), not drag nor windows. The inertia force is the strongest when the acceleration is fastest. So as you are sweeping from 30 to 70 mph, the load contribution from windows down or turning on the AC is changing. This will make your result difficult to interpret. Best to run at constant speed and measure mpg or engine load with window down vs. A/C vs. control. Engine load or mpg can be measured by an OBDII reader such as ScanGauge.

[@lemabikes5185]

I try to give an explanation for the 60-70 windows up-down. (3.247 - 3.242) From 30 to 60 the air flux goes straight on the surface (laminar flow), while over 60mph (around 93 km/h) the flow gets turbulent. You can try with your car and windows down. There's a speed just around 80-90 km/h when you can easily feel and listen to a change in airflow (speed depends on the shape of the car) Let me know if it a B.S. or not, colleague : )

[@lemabikes5185]

Lema Bikes See this pic, easier than my explanation (for each car, depending on the bumps of the body --> in this case the windows down, there could be a different point of transition I suppose) www.roymech.co.uk/images/fluids_95.gif

[@ashwinnambakam7656]

You might also add that if the car has Automatic Climate Control, the AC come on full blast for the first 5 or 10 minutes to cool down from 105 to 75 deg F for example, and then stabilizes to maintain 75... In that scenario, the AC is not using that much engine power to run, when it's just maintaining a certain temperature, so it might be much closer to Windows down, and break even between 50 and 60 mph, if I had to guess.

[@MediumHalf]

I kept trying to imagine the road layout that necessitated a lane change like clockwork in each run (or whatever it was that prompted turn signal usage).

[@gigglybeast]

9 years later, it looks like we’ll never know.

[@gt5458c]

Aero drag is trivial when the question is how fast you can accelerate this mass using full power. It's lost in the noise here. Fuel economy is mostly characterized by steady-state cruise conditions where you are using ~20 hp for long periods. In that case, 1-3 hp for extra aero drag or AC compressor power consumption becomes much more important. So good attempt, but this really isn't a good measurement technique to answer the question. Instead, how about driving at a steady speed and comparing fuel injector pulse width while manipulating the windows and AC as your variable? That's much more closely related to fuel consumption. Also tricky- AC compressor power demand is highly variable based on varying conditions, even comparing only conditions where the compressor is not cycling on and off. "Full blast" AC takes more power when the inside of the car is hot and a lot more power when the outside is also hot. So even using injector pulse width as metric, you need to check all of these states fairly rapidly or else changing inside/outside temperatures will change the compressor power draw.

[@nickamarit]

Windows down for autocross! :)

[@darthfunkninja9011]

I had always wondered if running my heater was making my car just a tiny bit more efficient by minimally reducing the temperature of my intake manifold.

[@anythingbenz4005]

DO MORE MODS ON THE INTEGRA!!!

[@Kirisame312]

I would have liked to have seen an "A/C on 50%" and "A/C on 75%" settings, as that's what I usually use. I know most people use Max A/C all the time, but after owning a car whose radiator would blow if the A/C were run at max for more than 15 minutes, I am wary of the max A/C setting. I do appreciate that you took the time to make this extra video though!

[@MrFriday83]

+Kirisame312 The compressor is still on, i doubt it would make a notable difference.

[@ThePsychoGamer1337]

interesting study but i think this would only apply to your integra i wouldnt be surprised at all if you got very different conclusions from something like an suv where aerodynamics may not be as good, or even older cars with less efficient ac systems

[@MicroSD16Gb]

You are missing: Windows down and AC on full and the control one: Windows down, heat on full and AC compressor on!))))

[@CaptainCocaine]

One thing of note that if you're driving 60+ mph, you should probably have your windows up anyway, as the wind noise can harm your hearing, especially in your driver's side ear. Same with driving with a crosswind at just about any speed.

[@Trainboy1EJR]

so in other words, if you have AC use it, because it's more comfortable (no wind noise) and causes unnoticeable difference in acceleration with an adequately powered car! anything under 180hp can suck it!

[@KingdomOfMog1]

Mythbusters did this didn't they?

[@TheSuthernMafia]

I'm liking the teg series, I have a 97 teg that I'm making my project car and these Vids r great pointers for me, one thing I'd like to c if it isn't to much trouble would be wiring as I have sum issues with my wiring for instance my brights r funky and my fuel pump has been rigged due to the previous owner so if u could do a vid on how to rewire that would be awesome thanks and keep up the good work

[@zackpedersen2666]

I know this is an older video, but what about Jeeps and Convertibles with Open-Air driving? What about a Jeep Wrangler with no top on it and no doors? And What about those weirdos that drive around with all the windows down completely and blasting the A/C at the same time?

[@OhPoWneDiel]

an alternative, more accurate could be this; go to a gas station on the outskirts of the city. fill up your car to the brim. then drive off to highway speeds, return to the gas station and fill up the car to the brim, then note the amount of gas used to top up, that would be = the gas used in the test run. drive off again, same acceleration and max speed now with windows open and note the gas used. repeat again with ac on. im telling you if you dont do this test i will do it myself and post on my channel

[@fs811523]

I think the tests would be more precise if measured at a constant speed. Like you said, in cases AC is on and you open fully throtle, AC is shut off temporarily.

[@reicht4]

you are giving left turn signal at same vel's? if merging to a line which means side run, could effect on your tests (of course with wind speed, weight, tire temps etc) but nice non cost experiment well done.

[@Jordanschintler]

Idk if you’ll see this or not but if you do all the info you give in theses can I still use on an automatic transmission or is it going to be different for mine

[@the-real-zpero]

My dad is one of those people who never turns on AC and says "i like to feel the wind" and meanwhile I'm sweating my ass off because it's 80 degrees

[@ssllhh100]

hi i'm no expert but i have some experiance under the hood , the heater is just a intercooler that runs the heat to the inside , its located under the center console , there is some pipes running in to it from the cooling circuit , so yeah heater on or off doesn't affect the performance unless the compressor is on

[@Mr.SixEyes]

Hello Jason, Could You Cover The Topics Of H.C.C.I. Engines And Pulse Width Modulation???

[@nathanatkins15t]

I think you should monitor injector duty cycle at a constant speed and roll windows down and up and cycle AC on/off

[@coltonburke17]

Would sound systems with amps and subs or even h.i.ds draw anough power to affect acceleration?

[@0Freguenedy0]

Now unless its hot like hell, i never turn my a/c on, thx for the video. Will save some money in the long time

[@NickWayne100]

Shouldn't the title be quickest acceleration? Not best gas mileage?

[@mariaboswell5596]

Hey what about the throttle wire on the other side how do you Tighten it up up

[@MobiusGT]

you should redo this with like a bigger car maybe with 4 windows such as an suv

[@brianruizy]

I've seen some cars, on circuit tracks, run the air fans at max , but with the ac off. Does anyone know why?

[@samfedorka5629]

Fans run off the electrical system (battery / alternator) so turning them on doesn't really have a performance hit like turning down the windows or running the AC does. It's the easiest way to keep the driver cool without taking a performance hit.

[@johnbarron4265]

@@samfedorka5629 Accessories running off the alternator impact performance no less than if they were connected directly to the crankshaft. The extra current supplied to run the A/C blower fan is accompanied by an increase in drag torque on the alternator, which eats into your engine's brake horsepower. The actual reason circuit racers may choose to run their fan full blast without A/C is that it takes a lot less energy to increase the flow speed of air than it does to cool down the airflow. The heat transfer capability of the air stream is enhanced dramatically even at modest flow speeds, as compared to stagnant air. Running the fan on max also cools the hot surfaces constantly getting baked by the sun more effectively. The most energy efficient method of cooling the driver involves blowing air at high speed and at a temperature just a few degrees cooler than the driver's skin temperature. You can try this yourself at home. During summer, when it's warm outside but below 90F, take a fan outside, have it face you at point blank and turn it on max for a few minutes. You might start to get chilled, even though the air blowing over you is a lot warmer than the stagnant air inside your home.

[@7150285]

high speed windows up and low speed windows down. That's what I always do

[@Steve-hh9gs4yo2i]

Gas mileage is near the bottom of the list of priorities to me when i buy a car.

[@joshuaburton8106]

I drive around with my windows down and either A/C or Heat on..

[@marj736]

liked and faved. excellent experiment! EE!

[@aesopm9200]

coastdown test windows up vs. down would be fun?

[@Klattooss]

No 'Thanks for watching'?

[@decibelOW]

How old is the car being tested?

[@aZnCdn]

Love your videos. I try to drive with the windows down as much as I can in the city. I notice a 3-4 mpg difference when I have the ac off.

[@RafaGmod]

The aerodynamics are a complicated point. Maybe your car have more drag at 50-60 than at 60-70. It's almost impossible to know the real path of the air... Maybe a constant throttle can be a good experiment (observing the speed variation on a flat street).. Maybe a braking can be good experimento too. Accelerate at certain speed and press the clutch. Then get the times between certeain speeds. And in the case of the A/C, acc to a certain speed and release the throttle and get the times... Maybe it would work! hahaha

[@wallacedavidg]

Mythbusters® tried this experiment driving two SUVs around a track. One had the AC on the other with the windows down. It's the answer to the age old question that still evades our understanding. I think the best test would be to use a measured amount of fuel and see which goes further with cruise control on while driving a circular track.

[@therealRustyShackleford]

Wouldn't the compressor cycling have an effect on such a small window of time you are accelerating? Seems the test should be much longer to get a better average of power consumption (fuel usage) than just a short test when just maybe the pressure switch has compressor disengaged.

[@MrDieselakias]

useless boring

[@rippin187]

You will find that parasitic drag will not dramatically affect modern cars until very high speed, around 110+ MPH.

[@SrTuX]

You forgot the weight of the car is affected by the consumption of the gas, was the gas level the same on all the test?

[@EngineeringExplained]

Yes, and runs were alternated so fuel weight wouldn't be an issue.

[@Yadiel458x]

Which is more fuel economy efficient, A/C off Windows Down or A/C on windows up?

[@CaptainCocaine]

WATCH THE GODDAMN VIDEO

[@SirXyloid]

I used to have a 1987 Mercedes 300SDL. It had leaks in 5 of the 6 injector seats (or seals, o-rings, heat guards, etc. everyone has a different way of calling them) so the car lost a lot compression from that and therefore power. I remember I'd never like to turn the A/C on because it would drain the fuel twice as much as it already did. And oh the power loss. It would struggle trying to spin that A/C compressor. The heat made no difference. What I loved about it was if you put the heat on automatic before starting the engine after it cooled down, it would start off not even turning the blower on. After the engine gains a little heat it would gradually blow harder and harder until the cabin temperature reached the thermometer temperature, then it would start slowing the blower down. For an '87 I thought that was impressive. I've yet to see that on any other car, even newer early 2000's cars (I rarely am ever in a late 2000's car).

[@MrFriday83]

I've always got a good laugh when I see a c-worker come into work soak'n wet, because he tries to save "money" by not running his A/C in his big diesel .(Where I'd assume the percentage difference is even lower than what you showed in a lowered powered car.) I guess, his suffering nor the likely interior damage from the high humidity is factored. Thank you, ill be sure to show him with a big told you so.

[@mikeyc5360]

Love your videos! I do think that there are too many variables to get an idea of efficiency based on acceleration. Engine output can vary several percent from run to run just from things like knock sensors, heat buildup, PCM adaption, and other factors. If you want to isolate just the wind drag, I would suggest doing that via coast-down on a calm day: same stretch of road. To measure fuel economy, you really should hook up a small fuel cell and measure fuel used, although you might be able to get away with measuring injector pulsewidth over time using a data logger.

[@SnowRaptor]

Great videos, man, The only thing I thing I think you could improve in your analysis is comparing the %difference with the standard deviation from your averages. If the %diff is less or about the same as your standard deviation, the difference is not statistically significant and you should consider both runs identical for all intents and purposes. I can't wait for the data logger-based comparisons!

[@JesusMendoza-gj8jj]

Maybe removing the compressor fuse would've made for a more accurate experiment.... I'm sure nothing significant.

[@HyperSpify]

You need to redo all of the tests instead of just keeping the results from your last video, because the temperature and humidity will vary from day to day. Also, you should randomize the trials instead of doing all of the runs from one category and then switching to another category.

[@CommaCam]

I wonder if you would see any longer term benefits from keeping the heat on at all times but having a simple way to regulate it outwards rather than right on you (especially in the summer).

[@papey9th]

when you are driving from 50mph to 60mph it looks like you are turning left, maybe this is the reason for the windows up vs down diffrence.

[@YusufSheth]

Glad to see you revisit this. I'd also like to see some fuel efficiency and part wear comparisons for engine braking vs. braking in neutral.

[@dirtsailoroff-road5580]

Damn, I'll use my heat at the drag strip

[@kjacobs1693]

Good job getting the control in there. I went to comment on the previous video. then realized you posted this one.

[@matrix777able]

Hello I truly think your vids are great keep up the good work . Don't worry about the haters

[@iceman5943]

I ran my ac today for the first time in about 6 months and it bogged the engine down so much

[@travisli-rufus1949]

Window down, ac off, heat on. Help keeps engine running cooler and healthy!

[@kevincarr5287]

what car is that? its not your sti....

[@EngineeringExplained]

My Integra

[@drumphil101]

I don't feel completely comfortable accepting the number of significant figures quoted for the timing data. I'd be very interested to see how you can claim to the nearest millisecond. I'm not bashing it, I'm genuinely and honestly intrigued! Just seems like there's an awful lot of variables, so the error bars would be fairly substantial in analysing any trends presented. Any explanations of your expectations for experimental accuracy would be appreciated just for peace of mind!

[@EngineeringExplained]

I explain the methodology in some of the previous videos, but essentially I use 120 fps for the timing, and count the frames, giving an accuracy of 1/120 of a second (something like 0.008).

[@drumphil101]

Thanks for the quick response, I appreciate it. Just out of curiosity, have you ever calculated the experimental error for your results? Either that, or just the variance in the data set? I'm just wondering how reliable the %differences that you calculated are, since some of them are very small. Thanks for responding either way, and keep pushing the awesome content, I always enjoy it!

[@SnowRaptor]

I agree with drumphil101 that you should include the variance (or standard deviation, depending on your methodology). Comparing the difference with your statistical error is important. For example: if your standard deviation between the three runs is around 1%, an 1% difference between Windows up and Windows Down is statistically insignificant and you should consider both equal.

[@MarphyW]

Jason, in general I really like your videos and the methodical approach you are usually taking. I can understand it would be a significant effort to record all times again. However, this way the video is kind of pointless. You are experiencing equal or better acceleration with windows down, that should make an engineer wonder why. You made the new measurements quite a bit later, under different conditions, maybe even with different tank fuel level. And you are comparing them one to one to the old times. You should have made at least a control run with windows down again to be able to bring the new measurements in a correct relationship.

[@EngineeringExplained]

All of these runs were done on the same day. I just didn't put all the data together the first time.

[@Psysan]

From aerodynamics theory, you'll see that drag is influenced mainly by the frontal area of the car. So you can actually expect those times to be barely different for a street car.

[@MarphyW]

Engineering Explained Thanks for clarification. Then it's perfectly fine.

[@OhPoWneDiel]

can i offer another idea on how to test for fuel economy. lock the car on cruise control and do these tests, on the same stretch of road, at the same speed and read off the average/instantaneous mpg each time. for example i travel on the same road everyday to work, and i have observed the mpg with windows up/down. ac off/on, and i can confidently conclude that AC on always have a a higher mpg, actually even more so significant than your results, because your result are more to do with time than the actual mpg itself

[@DENicholsAutoBravado]

On the surface instant mpg looks more accurate, but it's only as accurate the sensors of the car can be guessed at with an algorithm. Many cars can't even see fuel flow or pressure, not by the car's computer. OBD II is very slow...the PCM itself is quite quick, but this universal communication being relied on for such finite data, would probably be suspect. Not saying your idea isn't good, just that every format of testing has it's issues.

[@OhPoWneDiel]

however though, instant mpg is close to real mpg and always closely match my calculations. haha you are invalidating me saying sensors cant actually see mpg, but this video is doing the exact same thing, measuring acceleration and then simply assuming its =mpg

[@DENicholsAutoBravado]

OhPoWneDiel It is a good visual test that he could come up with. What I like about your instant MPG is that when that wind gust hits your car that you wouldn't have noticed, your instant MPG drops or goes up and you're like, "Oh, wind gust." What fun is when the wind gust actually helps. :) An advantage of his test is that you can more clearly see the affect of A/C on power that gets to the wheels. In that it's actually more enlightening. I've noticed that at WOT on my car the instant MPG varies greatly even on the same street going to work every morning. Hmmm, on such a channel, we're very careful about potential inaccuracies. I'm not at WOT every morning, I'm just at higher acceleration, as I've found finishing my accelerating a little sooner lets me spend more time at efficient cruising speeds.

[@ninhbac04]

How can you drive with the heat on full it's 80 degrees outside.

[@Kepe]

Ever heard of a sauna? :p

[@ninhbac04]

Yep.

[@ninhbac04]

Sadpants McGee Let me know what a heat stroke is like

[@CaptainCocaine]

Indie Guy He's doing it for maybe a minute each time. That's not going to stroke a relatively healthy adult.

[@Kepe]

A human can spend over 20 minutes in a 80 degrees Celsius (~180F) sauna without any issues. So you could probably spend hours in a 50 degrees Celsius (~120F) car if you just keep hydrated.

[@user-wt2ky2uq4k]

thanks for redoing the video :)

[@prodrivebrasil]

Great video! Thanks! :)

[@3ne2nr4life]

hey bro, wats tthe plaque besides you white board?

[@EngineeringExplained]

3ne2nr4life KZbin sends you a present when you reach 100,000 subs. :)

[@3ne2nr4life]

Oh ok, pretty cool... Well you do a great job anyways..I'm glad you didn't sign up to go to mars and weren't chosen.. we need all the mech/techs going into the near future...

[@MrRacs1]

Hey 😊 I've got a question. The new Nissan 2015 lmp1 car use a flywheel to store energy from breaking, but how do they make sure the flywheels speed keeps increasing as the car is slowing? And when they deploy the energy stored, how do they make sure the car accelerates, when the flywheel must be losing speed? Love your videos and hope you know the answer 😊 Robin

[@EngineeringExplained]

I'll have some great videos on this soon. Be sure to like my Facebook page as one of the videos will be on NismoTV so that's where I'll share the link.