Do newer cars have an "audio in" jack, on the dashboard or center console, as part of their audio systems? Something you could use to connect an MP3 player thru the car's system. What auto brands, if any, have this feature?
I had a Mitsubishi 3000 that had an input on the dash. Many Blaupunkt after market units have an AUX input on the back and for $12 you can buy a cable adapter (eg, from Crutchfield) that lets you access this input.