i think its more of a mix of 2d and 3d, the cars and other stuff are sprites facing the camera, some with multiple angles like the cars but the road is made of polygons like standard 3d
The road is made of long sprites too, like a super scaler arcade racer like Super Chase. The ground plane is done with a mode-7 esque effect, and the environment is a mix of parallax and more sprites. I don't think I've seen anything yet that is using a 3d polygon.
