[Richie©]

Here is simple a simple one im using inside a timer that runs every second.
The speed is 450kmph coz i found out players with high ping could trigger it easy if it were lower.

pawn Код:

if(GetPlayerState(playerid) == PLAYER_STATE_DRIVER)
{
    new Float:x,Float:y,Float:z,vehicleid = GetPlayerVehicleID(playerid);
    GetVehicleVelocity(vehicleid,x,y,z);
    if(floatround(floatsqroot(((x*x)+(y*y))+(z*z))*250.666667) > 450) //detects if speed is more then 450kmh
    { // do your own thing here, warnings or something