This script adds manual ignition to all the vehicles in the game. There is no need to set something up in the .xml files of the vehicles.
After you entered a vehicle, a little hud appears on the bottom left side of the screen. You have to preheat the motor by pressing the startbutton once. After a little amount of time the preheating is finished and you can start the motor by pressing the button again.
ManualIgnition (file size = 20 KB)