You are correct ! 3DO's RR's road is completely scanline! Not a single 3D angle adjustment! And while at NFS, you can clearly see the polygonal curvature of the road, in the 3DO's RR, the road is pixel-smooth curved. The hills go up/down, curves turn left/right exactly like in any other scanline-based racing game.
yes.. i also think is basical the "old" roadrash with some 3d objects on the side plus the graphics are replaces by digitised trees, cars, bikers... what ever.
the typical eyewashing of that time
however the result is looking and feeling good
by the way i think crash n burn uses the same tech (2d scan + 3d sideobjects)
what i wanted to say: if you handle to align some 3d environment (in sum max up to 50% of screen) attached to the 2d scanline engine, you are the man!! you did it!!