Buying an Audi 2018 
2015 BMW 5 Series Sedan 528i 4dr Sedan (2.0L 4cyl Turbo 8A)
Beware of the restart shudder
 When the eco Start/stop engages and the engine restarts, the restart is hard and causes the car to noticeably shudder. Dealer told me I could turn off the start/stop, but then I would lose fuel economy. I think they fixed it for the 2018 model year, but make sure you test it before buying.