i know this may seem more thermostat related but is also MPG related:
Took car to indie garage that is well respected round here (and also seen good reviews on here) as i have never seen my temp go above 70, even after long journeys, everything else (heaters etc) seems fine. Left the car with them, ambient temperature about 3 degrees.
Went back at the end of the day and the guy said nothing wrong with stat, he had left the car running, it had got up to 90 and the pipes were running warm. Told me that in the current cold weather the temp won't go up high (I did point out that I had driven it for 2 hours on motorway when temp was about 15 degrees and it hadn't gone past 70).
Anyway, couple of days later (air temp about 5 degrees) I drove it 50 miles and when stopping for fuel checked the top hose which was indeed running nice and warm. (Gauge showing 60-70 degrees)
So, everything seems to work, I get ok MPG (32 for town driving in a 1.8 SW) and all my heating works perfectly. Would I be right in guessing I may just have a crap gauge and that I should just stop worrying and put it down to an "alfa thing".