Whilst I can’t say for sure, I would say most tunes listing speeds that high are using a glitch/bug (like the aforementioned 30fps glitch)…I have used quite a few top speed tunes recently and none have been able to get anywhere close to their purported speed…highest I have managed was 313mph on the M68. That 320mph+handling tune (assuming it’s the same one I used) I believe, if memory serves, I got it to 290mph.
As to the clipping into the ground, the 300mph+ tunes tend to do that as the rear suspension is soft so it pushes down over a certain speed which gives you the top end speed but will make the car difficult to control. There are some tunes, however, that do manage to combine both…the one I use for speed traps (can’t remember it’s name) can combine 310mph+ speeds whilst still being controllable (it can still handle 300mph+ round the relatively sharp left hander a mile or so before the speed trap coming from the South)
Night of the living thread… I don’t think there’s anything you can do, those top speed tunes have super loose suspension setups and combined with the aero on the EVO it pushes down and since there’s no “scrape” mechanic in the game it just pushes into the ground
That clipping into the ground is the basis of all those 320+ mph tunes.
That car can’t normaly go that fast.
By messing around with the aero and the suspension you can get it to clip into the ground in a way that screws over the aerodynamic drag calculation. It break a part of the driving physics and allowes you to drive faster then should be possible. You are exploiting a glitch, and that has some side effects.