I had to stop the chaps using the hand throttle on our Land Rovers, setting it to around 10 mph out on the airfield somewhere, then both jumping out and running round the vehicle and swapping seats!
It was great for setting out glims for night flying though, get it chugging along nicely at walking pace, get out and walk around the back then offload and turn on the glims as the rover puttered along on its own..