The trick may be finding a 2" receiver hitch for an A4. I never found one for my '98. All were 1 1/4", which matches the maximum tow ratign for the car.
Look into Bosal hitches. They're a European brand and are the factory/dealer installed hitch for VAG cars in Europe (my TDI has a spot already molded into the spare tire tool caddy for the Bosal hitch ball assembly). They aren't cheap, but attach to the chassis much better than the crap-tastic hitches sold in the US. The catch is you'll need to have a 2" receiver fabricated to fit the hitch assembly to use std accessories.
Look into Bosal hitches. They're a European brand and are the factory/dealer installed hitch for VAG cars in Europe (my TDI has a spot already molded into the spare tire tool caddy for the Bosal hitch ball assembly). They aren't cheap, but attach to the chassis much better than the crap-tastic hitches sold in the US. The catch is you'll need to have a 2" receiver fabricated to fit the hitch assembly to use std accessories.