Golf 2005 TDI Thermostat

Hi, my girlfriend has a VW Golf TDI 2005.
 
I am asking here since I do not own a VW and I am a bit unfamiliar with the car and diesel engines...
 
Her engine does not seem to be heating very fast...It take a while. Well it takes quite a bit longer than my gas car. Is that typical of a diesel engine?
 
If not, could it be that the thermostat is malfunctionning and when the car is started, even if the engine is cold, indicates a hot engine thus cooling thru the rad and so it take a long time to get to appropriate temp?
 
In other words...I would need to know if it takes the same time to heat that a gas engine, there is a good chance the there is something wrong with the thermostat...
 
I am not sure if I am clear, but any help would be nice.
 
 

Hello,
 
I am French and a Golf V (2005) owner, and I'm not surprised to wait some kilometers before reaching 90 °C.
 
Sure, it depends of weather (winter or summer)...but diesel engine need more time...don't matter about your thermostat.