1997 A6 2.6 SE Petrol - Need your advice

[SanDan]

Hi Forum

I am new to Audi and new to this forum so excuse me my lack of knowledge. I bought 1997 A6 2.6 SE Petrol a year ago. It has a superb response and power but gulps fuel. On normal / long drives it used to give me about 30-35 MPG and in city about 25MPG. Recently I got the annual service (not Audi authorised unfortunately - to save some £££..!) and now it gives me about 5MPG less for both.

What should be the normal fuel consumption for this car?

Recently the coolant level has been dipping too often and too much. in about 2 weeks I have poured like 1 litre of anti-freeze and 2-3 litres of water. There seems to be a leak. The coolant temperature gauge goes upto 90 degrees in city.

What should be the normal temperature level in city & normal drive?

Could you guys share your wisdom with some good tips please.

THANKS.