Very similar suggestion as
https://www.roleplay.co.uk/topic/127467-some-cars-are-to-slow/
And the same comment I made on that applies here: In general, realism should in my opinion not be the main focus for cars performance, it should be server balance. And in general import cars have been super fast compared to the GTA ones, something which leads to generally ridiculous and stupid driving, horrible police chases and more. So the goal here should be to try and balance the cars around the standard GTA ones, that all go around 120 MPH instead of balancing it around real life performance.