Any and every European car has fuel gauge issues.

Paul, as far as coding the rear windows, it can be done but developer is required if I'm not mistaken. Certain modules get locked and you can't change coding in them without developer, if I'm not mistaken EIS would be where coding needs to be changed I remember being told it wouldn't provide power to any rear door module (since clks don't have rear doors) and the EIS is your first power up point.

Or.... Convert rear windows to manual roll haha problem solved!!