Total posts : 45366
It would seem that the capacitive coupling at 1600 kHz between the antenna feed point and the vehicle body through a magnetic mounting scheme would be minimal. The mobile HF ham antennas are usually bumper mounted and the feedline ground is connected to the chassis or bumper for grounding.
At VHF, the capacitive reactance is low enough that effective RF grounding to the vehicle body is obtained with a mag. mount.