Transmission, seals, every electrical item you can name.
This car is a piece of crap. I had to get it towed in my first month of ownership. My BMW never gave me this kind of trouble. I was warned that Audi and VW are electrical system nightmares and this just proves this. Terrible car.
The Quattro feature is nice but now BMW has an Xi 3 Series that's where I am going once this Audi garbage goes into the scrap heap. My 993 Porsche never gave me these problems either.
Give me a break. You obviously got a lemon. The majority of A4's have had great reliability. There is no need to bad mouth this car the way you have.
If his car is a lemon then he has every right to say all the bad things about it. He has probably paid nigh on £20000 for it so he should expect a good car.