Is that a coincidence?;-)
Do not trust instrumentation. Double check.
Engines are designed to run at an optimum temp range that is a compromise between thermal efficiency and the material specs of the engine itself.
Therefore running engine cold equals increased fuel consumptions/emissions and greater rate of engine wear.
Spookily enough - I am tackling this problem this very weekend on my daughters car which is off the road until I can get to the bottom of it! I will be using an infra red themometer to check actual temperature. Unfortunately I do not know anyone to borrow the thermometer from so have had to resort to hiring - costing £7 for the weekend + taxes.
It would of course be just as cheap to swap out the thermostat but the car in question is a 'pigdog' and I would have to drop the cambelt to access thermo, so do not want to do this unnecessarily.
230 TE (W124) 1989 with 153,000 miles on the clock - hoping for at least another 100K