Gotta go with Codetapper on this one, Lotus one for sure. Though not the most varied driving game ever, it was as good for the Amiga as Pitstop II was on the C64.
It finally showed what an Amiga race car game could be like,with smooth graduated hills/road effects,& was (in 1 player mode esp.),FAST-a far better illusion of speed than the like of Batman the movie's 3D effect which up 'til then had been regarded as decent 3d rather than the jerkfest that truly was!
Dunno about the roadblocks though-more often than not the CPU cars miraculously could fit though road barriers,overtake you & send you crashing to a halt whilst you usually needed at least two cars width to try & perform a similar overtake-very annoying!