I would do something like this:
- Give the car the regular old wander.prg as its runtime program (actually a car wandering around aimlessly crashing into things wouldn't be very realistic, heh... You'll probably want to give it a set path)
- As its activation program, give it this, assuming the car is item 0:
#eraseitem(0)
#destroyitem(0)
#newplyr("car.tem")
#walkspeed("fast") * or whatever in TK3...
#incar! = 1
Now you'll probably want to get out of the car at some point. Set this as a run time program when you press the "E" key (for Exit car, or whatever you want):
#if(incar!==1)
{
#createitem("car.itm",car!)
#putitem(car!,playerX[0]!,playerY[0]!,playerLayer[0]!)
#newplyr("yournormalcharacter.tem")
#walkspeed("slow")
#incar!=0
}