The insulation on roller doors is just a joke. I have a 5 mtr wide roller door.
On the new part (built 2013) of the garage, the walls and ceiling have 150 mm of fiberglass wool. The original garage (built 2002) has 100mm insulation walls and ceiling.
I can heat the garage when it is 0c outside and get it to 10C which is good for working in it in 40 minutes with 4 kw of electic heaters. The heaters start to swich on and off after an hour as the thermostats start to operate.
While Kingspan type insulation is twice as good, it was uneconomic as you are only using the garage when you are working on your car now and then. If the garage was being used 6 days a week in the winter that would be a different economic calculation.
The Harmann roller door is always running with condensation in these circumstances as it has the insulation value of single glazing. You cannot get enough thickness of insulation in there as the door has to fit on the roller above the door opening and there is only so much room for the roller.
Hormann and other door vendors have other types of door that have a good thickness of insulation and these tend to be sectional and side along a track and are parked on the inside wall of the garage to get the car in and out.
As always your money, your garage but a roller door is not a given, it is space efficient but very poor for insulation properties. I know from experiance.
My garage extension build.
http://www.mx5scotland.co.uk/board2/viewtopic.php?t=11902