ok, here's a few tips for speed challenge. Brakes are a complete waste of money, time and most importantly, weight.
In speed challenge all the controls except acceleration are dulled and slowed down. Therefore, the turns need to be made accurately. However, on most tracks, the roads are quite wide, and provide a margin for error.
Unless you are an EXTREME pro, on Nevada, NEVER attempt to hold down the accelerator the whole race. Against AI, just try to hold the straights. The stock brakes are sufficient, because you never use them. Just make sure that before a turn, let go of the accelerator, as this gives you more response and steering time. Otherwise, 300km/h+solid rock=
A car that most people suggest is a R34 as it is cheap, and can still keep up with the super cars...
I personally use a LP640, but I won all my other races with a R34
