The auto-off happens when the camera is on but has not been recording for a while.
I leave my camera on and use a small remote to switch record on and off. It's far easier to do this than to try and reach around to switch it on and off and it's not always possible to get someone else to do it. Leaving it recording uses up a whole lot of tape unnecessarily.
I spent a bit of time looking at various cameras a while ago and I ended up with the Panasonic I mentioned for a few reasons:-
It's cheap,
it's relatively light,
it's easy to get a big battery onto (a 12 volt supply is a better solution though),
it's side loading (this was an advantage to me because my camera uses the cameras mounting bolt hole as part of it's mounting and it's a lot easier to get a tape in and out if you don't have to keep unscrewing the camera).
This camera seems to be resistant to head dropout due to vibration, so far anyway.
Other choices:-
I would never use a hard-disk camera in a car (for what seem to me to be obvious reasons).
When compared to the High Def' camera I own and others I looked at, DV is the better choice for in-car use. (this would take a bit more explanation and I'm trying to keep this post as short as possible)
Lipstick cameras definitely have their uses.
The mounting measures mentioned are worth serious consideration. There are many different solutions some of which are difficult in a GT.
I think you'll find that there are reg's on how to mount them (here in Aus') anyway. I'll leave this for now as I have to leave soon.
As well as a better view, wide angle lenses may also make the speed look more realistic. A normal lens tends to slow things down a bit IMO.
This may be because of the lack of peripheral reference, not sure.
Try to get as much driver in the shot as you can, you'd be amazed how much it helps in later "diagnosis". It's also a basic form of data logging if you can see the gauges.
Last thoughts-
Anti-shake works! (The mechanical anti-shake systems worry me a little in this scenario and the digital systems work well enough in my setups anyway. I have never put a mechanical anti-shake camera in a car)
Zoom-sound can be a pain.
Noise-filtering can be great and can have side effects, it should be experimented with.
I'm sure there are people here who are much better at this stuff than I am so I'll shut up now.
Tim.