2007 M-B E350-80k miles. Runs great although with the cold snap 10F ambient air temp, the car temp will not rise above 70C~150F. As I slow down the temp gauge will actually drop closer to 60C. The thermostat is a 100C- OEM replacement, and in the summer the water temp is over the 80C mark. The air in the car is very lukewarm at best. Is this a classic case of stuck open thermostat? it is supposed to be electronically controlled, but it is clearly not functioning. Last, coolant level is normal, car never overheats nor runs hot either.