Your DoOnce is probably a decent approach for now, so that it doesn’t go machine gunning. However, 0.2s still allows 5 of the sounds to play in a second. Try and determine how quick you’d expect the object to be able to rehit and reset based on that. Simply extending the time should be better for now.
I’ve not used the Vehicle preset, so I’m also not sure on those collisions, but on your vehicle, try and add an impulse to your car in the opposite direction of the normal from the hit event. That way, you will bounce back a bit when hitting an object so are less likely to continually cause the hit event each frame.