Sout's Amiga Lotus games were something of a masterclass in how to use the blitter incredibly efficiently -
the unparalleled smoothness of the first two games came from actually drawing two frames ahead using the blitter*, and copying the pre-drawn frame ahead (in the VBL) into the display buffer. That said, he got it running at a decent enough clip on the ST too, which has no real graphics acceleration hardware. I'd wager than on the MD, drawing the cars and roadside objects was simply a case of using the sprite capabilities as they came, which allowed him time to work out how to get the road to update as smoothly as possible.
[* - And as I understand it, that's drawing pretty much everything with the blitter - player's car, opponent cars, roadside objects, sky, background and the road itself, which to my mind is a pretty good point to bring up when anyone calls blitter objects slow...]