Thanks to someone who backed into my car while it was parked a week ago, and it is no longer drivable, I have been able to do some comparisons between three brands of (rental) cars when it comes to AM radio reception. Assumption is that there is probably only one AM radio design used across all models of a given car brand.
Of the three, Chrysler came out the winner in terms of the two things I look for in an AM car radio:
- highs, lows and generally how music sounds off a radio station with a decent audio chain for music -- I used W-14-40 for my tests
- DX
Chrysler takes a more novel approach. They do not appear to have a (RF) noise suppressor on the ignition itself, but I suspect no one does anymore. Taking that into account, more lengthy tests on my previous car, a 2003 PT Cruiser, indicated that the AM radio has a Squelch-like mechanism that zeroes in on ignition noise -- at least from the PT's engine, not the car next to you -- and creates silence whenever the audio would be dominated by ignition noise. It took me years to realize this, until I turned off the engine at night and left the radio on: wow, instantly the receiver seemed a lot more sensitive and I was getting some interesting DX on frequencies that had been silent with the engine on.
While I'm not suggest anyone buy a car based on the quality of the AM radio, I am surprised that car manufacturers (or, more accurately, their suppliers) make the effort to thoughtfully design the AM side of the radio. Then again, despite the cries that "AM is Dead", there is almost always an AM station at or near the top of the ratings.