RotVelocity Stops Working When Seat is Occupied?

Trying to script a car. Applying RotVelocity to the wheels when the character presses W. But for some reason, when the character sits in the seat on the car, RotVelocity just stops working altogether. The car doesn't move at all. Not sure why this is happening.

Also, can someone point me towards where to learn to script a car? For some odd reason, I can't find any "script a car in roblox" tutorials. There are ones that will teach you how to build a car using welds and constraints and stuff, but I want one that will teach you how to properly script a car. Because honestly, I don't know if the way I'm doing it is the most efficient way. When I apply RotVelocity to the wheels, the wheels slide and stuff, and most of the time, the car will go forward a little bit, then just stop.

If anyone wants it, here's the script:

-- Created by TheEthanMaverick

local player = nil

-- Normally I'd use the Touched event, but it was having an issue where sometimes the player would
-- occupy the seat without "touching" the seat, so the Touched event would never fire.
while true do

    if script.Parent:FindFirstChild("signal") ~= nil then

        player = workspace:FindFirstChild(script.Parent.signal.Value)

        while true do

            if script.Parent:FindFirstChild("signal") == nil then
                break
            end

            if player.Input.Booleans.W.Value == true then
                script.Parent.Parent.BL.RotVelocity = Vector3.new(0, 0, -100)
                script.Parent.Parent.BR.RotVelocity = Vector3.new(0, 0, -100)
            elseif player.Input.Booleans.A.Value == true then
                print("A")
            elseif player.Input.Booleans.S.Value == true then
                script.Parent.Parent.BL.RotVelocity = Vector3.new(0, 0, 100)
                script.Parent.Parent.BR.RotVelocity = Vector3.new(0, 0, 100)
            elseif player.Input.Booleans.D.Value == true then
                print("D")
            else
                print("none")
            end

            wait(0.1)
        end

    end

    wait(0.1)
end