I just got an XF fairmont on LPG. The first thing that i realized which didnt seem right was the unstable water temperature. The engine is getting overly hot and takes very long to cool after being switched off. The temp. gauge most of the time stays on the 1/4 mark and only moves when the thermostat opens. Then it goes over the halfway mark while driving and stays there and comes down a bit goes up and goes back to the 1/4 mark. Sometimes it looks like it will overheat.

IS this normal for a LPG driven car? Does LPG burn hotter than Petrol?

Yes, the engine will run hotter if the LPG setup is to rich. Check your t'stat and radiator condition too. And whether the clutch fan is working properly.

thanx for the tips