[Sjn]

I was one of the person to get tired of this issue. A while ago, I did some research with the Z position after I saw one of the post by Vince. I did the following to detect it; get the vehicle's velocity and store the Z value in a player variable inside a speedometer timer. So, when a player is falling from Mt. Chiliad with a vehicle, the Z value goes bellow -1.0. So, I check inside a timer that if the player's speed is higher than 320 and at the same time the Z value is still above -1.2, ban the player. If the Z value is above -1.0 but the speed reaches 350 then it's obviously a speed hack. I have tested this system and works quite good. You could try doing something similar.