Agree on 20" rims. Alloy rims too. They look nice but cost extra, need more work to keep clean, and then if you get steelies for winter, you're stuck with with a car that keeps changing looks, depending on the season.
I dislike seatbelt chimes and auto-locking doors. I often start before getting the belt on (sometimes I'm doing musical cars in the driveway and not belting up), and the locking doors seem to always need to be unlocked, like when I need to get out but left the car running.
Wife has taken a dislike the auto-dimming radio display in her new car. It's does not do a gradual fade: it just drops down, or shoots up. Worse is that it will jump between the two during dusk, like when you drive under trees and then back out. It might be a setting somewhere, she's not sure, but if it would just fade up and down it wouldn't be so bad--or just didn't change at all, that might be better.
Speaking of which, I'm reminded on my truck, the dashboard lights would dim when I turned on the headlights. Nice during night time. But often on road trips I would flip the lights on "for safety" which meant I'd have to turn up the dashboard lights so that I could read them, in particular the radio. It was a feature that didn't actually help me. [Oh well, it's traded off now.]