Headlight dimmer switches...Cadillac had an "electric eye" dimmer in the 1950s. Current technology could easily be used to optimize headlight output automatically.
Auto ashtrays and cigarette lighters..already some cars have non-smoking packages that eliminate these items. The cigarette lighter could be an after market item as the lighter socket is used as a power supply.
Or just be their own iPod, all you need is some flash memory, maybe WiFi to sync with your computer, or to just sync with your cloud storage when you're parked in the garage.
Nah, my car already has that. 15 years from now, your car will sync itself wirelessly with the cloud and will have your entire music library already downloaded.