I distinctly remember iPhones complaining about "obsolete device" when plugging them into a few years old Audi and VW cars around iPhone 4 era. That was then followed up with connectivity and charging issues.
I have an old car and it definitely doesn't work with anything newer than a 2G iPhone. No errors indicated, just can't hack it. It does work with a usb stick full of mp3s, though.
Could be FireWire charging--the original iPhone and earlier iPods could charge off 12V (FireWire), whereas the 3G and up only took 5V (USB). Adapters were available (although Apple didn't make them themselves)
Also with the early iPhones, if accessories were just "Made for iPod" certified but not "Made for iPhone" (which usually required TDMA emissions testing and iPhone testing) a message would pop up.
So what was the deal with that?