You could also make a 144/440 dipole that you can tape inside of one of the rear side windows. It could be made from really thin wire like 22 gauge and held in place with clear tape. Nobody would even see it unless they were really looking for it. Just adjust the angles of the VHF dipole elements to get them as horizontal as possible but still a few inches away from the steel sides of the vehicle. If you wanted to be really clever you could put one in each back window (right and left side) and run coax to a Wilkinson divider at the center console to combine the antennas, then a short piece of coax to the radio.