I just purchased se s line quattro last week full audi service history just so that i new it had been looked after properly as its my daily runner. If your concerned about mpg go for the diesel but if you love to drive then it has to be the petrol either way they are great cars as for the red fading as far as i know it still happens to a certain degree but good wax should reduce the risk and if nothing else a good t cut will refresh it