I was saying that the antenna needs a groundplane to work properly, the metal under the antenna in the roof or the trunk lid is what creates the groundplane. Having a ground strap to some metal "next" to the antenna like the car on a hitch mount or mirror mount on a truck is not the same. An antenna in the center of the vehicle with something to "push" off from like said before will always work best. When you have your antenna mounted low on the vehicle the steel of the vehicle just serves to block your antenna from radiating and it compounds the problem.