Lots of folks make mounts to hold handhelds. Some of them, like the Lido mounts only use spring pressure to hold the radio. This allows them to become a flying missile in the event of a crash. Here are two who make good, solid mounts:http://www.ram-mount.com/hamradio.htmhttp://www.gamberjohnson.com/
The other important thing to remember, is to keep the mount away from SRS devices, and vehicle controls.