I don't think anyone limits their car like that...
Unless I've misunderstood the posts in this thread, they do:
when I used to frequent Europcar for rentals I have seen some strange ways to limit the cars, such as something fixed to the bottom of the go pedal to stop you mashing it all the way down.
But I have not seen any proper sophisticated limiting. Probably too much for these rental guys to manage.
Yup, throttle stops are quite common on American hire cars.
Starting to become more widespread in the UK as well.



