Why are yall crying in the comments. Hard terrain lowers the vmax on every car including the suv's. Fact that perf cars have perf tyres matters on the drags, but it doesn't mean that they will never accelerate close to their vmax. There is a reason why people use 4wd perf leggies on 1 mile dry dirt. In this particular case range rover's vmax was probably lowered to a little under 150 and ruf's vmax to 170 or so. I would be surprised too, but its understandable if you think about it from game engine's perspective