RE Audi 90 10 V fuel consumption

[Rick Hayllar]

I am still get gathering data about my high fuel consumption i.e. my 90 
10's .
Another symptom is that the engines takes ages to get up to temperature 
and cabin heater starts getting mildly warm almost a soon as I start the 
engine from cold.
This makes me think that the thermostat has jammed open or maybe its not 
there at all.
Any comments from the members of the brain trust would be appreciated
Rick Hayllar