How can I keep a vehicle constantly accelerating forward? How can I disable reversing?

I want my vehicle to always accelerate regardless of user input, and I want to disable reversing on the vehicle as well.

The following script doesn't work perfectly because the throttle flickers between 1 and 0, and also the player can still reverse and cancel the script out completely.

while wait(0.01)do
	if script.Parent.Occupant ~= nil then -- If someone is riding the car
	script.Parent.Throttle = 1
	end
end