Yes, I've been thinking of selling my A4 for a while now - although it's the 1.8T petrol engine and not a diesel. The economy is great though, averaging 35mpg on most runs! The car is an 04 plate and I'm only the second owner from new. It has fully Audi Main Dealer service history from new, only 45k miles and full S-line spec. Recently serviced, TAX'd and had four new tyres fitted.
The car is immaculate, I don't smoke or have any pets. There is NO dents or scratches and the car is regularly waxed and kept in our underground car park over night.
The only mod I have done is had a fully Revo done by the local Revo dealer near me. This improved the performance massively.. The car is very fast, and the torque is great fun! The bhp went from 190 to approximately 230bhp and the mpg was improved!