I listen to quite a bit of AM radio when I drive. AM reception in my area is not very good and on long drives I lose my normal 24hr news station. So I use the iphone as a digital radio. However, I get a bit of engine noise on my iphone when its plugged into the 12v socket. This is not uncommon, but annoying never the less. So in case you play your iphone or other mp3 player in the car while getting power from the cigarette socket; here are a few tips..
1) Turn your device up as loud as possible and manage volume via the car stereo.
2) If your car is older, you can reduce noise by replacing your spark plugs and distributor wires, to noise suppressor type wires. If you have these types, perhaps its time to replace them.
iPod radio transmitter
Chris,
Good thought! I am in a small town in Iowa, but a Chicago sports fan, frequently frustrated not getting proper AM reception. One additional trick to consider is a wireless iPod FM transmitter. "If you want a cheap way to hear your iPod on your car stereo, FM transmitters are the way to go" according to this site.
FM radio connector
I used to use a FM broadcaster to my stereo, but I found the slight background noise and poor quality an annoyance. I found that going through the trouble of connecting via a cassette or through the AUX in the back to be worth it. The plus side of doing this, is you can use an adapter with a microphone and 'tada!' Hands free! :) More on that here... I would have to say though, when I was using FM transmitters, they were not good quality. I may have to check into it again now that we have better devices on the market.The link you provided looked pretty good.