On: I wish my web server were in the corner of my room

[Aeolun]

I’m fairly certain we’ve recently fought to open a rented car because the keyfob died and the way to extract the key from the fob was non-obvious.

Then when we finally got inside, the car didn’t have a keyhole to start it at all. Ended up calling the rental agency that showed us how to invoke the magic sequence by holding the (empty) fob in front of the start button for a few seconds before pressing it. I guess it does passive RFiD or something?

Anyway, that’s the point where I decided modern cars are not my thing.

[hunter2_ → Aeolun]

That's the immobilizer chip. It's a little pill-shaped RFID-like thing that's been inside keys since long before remote locks and push-to-start. Basically any key that has some plastic instead of being entirely metal. The reader is located immediately next to the ignition key hole on the steering column, and that location is sometimes used even in push-to-start cars although apparently in your case it was near the start button instead. Distance is limited to a couple centimeters max. Car won't start unless the immobilizer's reader sees the correct key. When a push-to-start fob's battery is in working order, the distance is moot because it uses full blown RF instead.

[Roark66 → Aeolun]

Modern is a subjective thing. I have a golf 5 from 2005 (tdi). One day I had to go somewhere and it turns out the car starts and shuts itself down immediately... It turns out the ground connection to the dash was intermittent. The dash for some unknown reason is the place where the immobiliser code/certificate is stored so when you start the car the Ecu has to talk to both the immobiliser coil next to the key and the dash.

I'll leave it to readers imagination how long it took me to troubleshoot the issue.