To be correct, there are three possibilities. If the car has the old, square front, it will have a 60 litre tank under the car, and most likely a hump in the back of the trunck under which an additional 22 litres tank is hiding. Total 82 litres. On these, the connection pipe (Y-pipe) between the two tanks is prone to leakages with ages, so investigate!
If the car has the new front and independent rear suspension, it will have a single 80 litres tank.