2003 (?) Volvo V40 Diesel: TBH, the car radio. Having a place of my own to play as loud I want was really nice. Second to that, the seats.
Funny, that with Volvo being known for safety and all, I had to sell this car, because from one day to another the brakes stopped working without me almost not noticing until I was on a major road (rural area and engine breaking to the rescue). Someone said, the brakes breaking was a economic crash for the car.