I have done a bit of research, and found the following. Hopefully it is accurate - you really need to check things out before you tow, to make sure firstly that your setup is road legal, and secondly that it will be a stable combination.
The Audi - 4WD with a front engine, 130BHP at 5,700 RPM, 136 lbs/ft at 3,500 RPM. Quite a perky engine, but you will need to run at highish revs to exploit the power and torque available. Weight is 1,134kg. If this is the kerb weight (check your handbook) then you should aim to tow around 85% of this figure - 960kg. That isn't a lot of caravan. The 85% figure is a guide not a rule, but it's a sensible starting point.
I can't say much about a Sprite caravan without knowing a year and model number. There is a 1991 Sprite Alpine advertised for sale as follows: 13' internal length, 2 berth, end kitchen, oven, shower, cassette toilet, double glazing - unladen weight approx 700kg. So there is definitely a Sprite that can be towed by your Audi. If you post again with more specific info, then I'll be able to help some more.