Heated seats are pure win....
....Nah, they're gay. Who wants a hot arse?
Heated seats (and steering wheel) are an important part of an integrated thermal management approach to reduce unncessary engine loadings: by fitting heated seats (and steering wheel, not an option for our Golfs I'm afraid) the energy required to heat the cabin and any occupants to what is regarded as "comfortable" level can be reduced by up to 35%, which is not insignificant.
@Robin what this means is less engine power required to drive the alternator and ancillary devices and more power available for moving the vehicle.
More information on thermal management is available in this paper, amongst other sources:
http://www.nrel.gov/docs/fy10osti/47416.pdf
/thread derailment
....What scientics regard or term as "comfortable" for the car cabin occupants, and in particular the driver, will vary from individual to individual. For example, I feel distinctly uncomfortable with a car heater on for longer than just a few minutes to up the general temperature and I might even begin to feel drowsy. I am more comfortable using my clothing to adjust my body temperature and comfort.
The fact that you can hear the engine's revs change, if at a standstill, when switching on the car heater or demister etc clearly demonstrates that more energy/fuel is being used. However, I don't personally care two figs about energy efficiency levels when driving. I would never want to buy an electric or similar car because I would miss hearing the engine sounds which I enjoy so much.
So if I understand it correctly, by not using features such as the heater and/or heated seats, a car has more motive power available. That works well for me