You can use any dashcam in multiple cars, it is just a matter of how it is connected to your cars and the mounting system. If you can live with the hassle you could use a single dashcam and 12v connector and transfer it all over when you switch cars, but the most convenient way would be to have a power connection in each car, then you would only have to transfer the dashcam. If you used a sucker mount for the camera itself it would take a few seconds to move it across, alternatively you could use a sticky mount in each car which would probably be quicker and easier when moving across. Most dashcam suppliers sell additional mounts and power supplies so you could have whichever arrangement suited you best.