(im sorry for only using English) but you made a wise decision. i've travelled from Bucharest to Craiova oftenly and its 4h to go both by train and car, theres no difference. in the 1980s, the train journey from Bucharest to Craiova was just two hours but sadly there are too many "temporary" speed restrictions. soon the same time will be achieved by driving a car.
they do exist, but the original ones no longer exist since they've been modernized. they're a common fixture on the București Nord-Brașov local train, which i sometimes take to go trainspotting.