The front page story in the San Jose Mercury today said that people are using Palm Pilot<br>III's IR port to unlock cars. They said not to worry, since most US cars use RF instead of IR.<p>Not that I'm particularly worried that someone's going to steal my car with a Palm Pilot (there's a lot of cheaper devices that do the same thing searching for car alarm codes and garage door opener codes, and my A4 alarm didn't prevent someone from stealing the ski racks straight off the roof), but does that imply that Euro cars like the A4 use IR instead?

The only cars that I have seen that use IR are Grand Cherokees. You can tell if a car uses IR because you have to aim the remote at a small black ball somewhere inside the car. I think Mercedes used IR for awhile, but RF proved to be much more reliable.<p>Not to worry, nobody with a Palm Piloit is going to steal your Audi. However, I am not sure how the Audi RF sysytem works. On many amftermarket alarms the alarm "talks" to the remote and changes the code after every use (to prevent theft). I would assume that our A4s do this, because if not they would prove incredibly easy to break into.<p>-Stu Koch<br>99 2.8qts

If it changes the code after each use, how come I can use two remotes? Say I open the doors with one, it would "reprogram" itself from say "010" to "100". How would my poor second remote know about that?<p>- Stan

All remote locks up until 1996 were IR based. This applies for the A90, A100, and the A100 rebadged A6. From 1996, even the "fake" A6 had RF.<p>- Stan

I would guess that the car keeps track of each<br>remote's code separately. It would be easy to check (if you had enough 'extra' remotes) Just keep configuring additional remotes to work, and see if the first one stops working. I'd bet that the car can't handle being programmed for more than four remotes at a time. (Maybe just two.)<br>