Why not just lift off the pedel at 15 MPH but have the gearing to have a little fun like 25-30 MPH?
make a clamp for the throttle or the gas pedal to limit the speed and take it off when you wanna go faster.
or put a block underneath the gas pedal so it only pushes down so far
Unbelievablejust tell them unless u want to have a push rod in your back DONT RIDE THE GAS.