My mate told me to go easy on the heated seats as they use loads of fuel. I had a look in the owners manual and there is no mention of it using fuel in there. It just states not to keep them on too much when the engine isn't running or it'll drain the battery.

Anything that draws current from the battery will inevitably have an adverse impact on fuel consumption (there's no such thing as a free lunch after all). Whether it's significant enough to worry about is another matter though. I personally wouldn't worry about it, although I'd probably advise not using it for too long without the engine running.

I shouldn't worry about it!

As above, anything used will have an effect on your consumption. but i'd rather have a cool ***** then worry about .5 of an mpg

I echo the answers above however my question is the following, does anybody find the seat cooling to be a little under powered? I dont feel much in the way off cool air at all.

Put it this way, I know when mines on and working, although I don't think you really need it when the A/C is on. I mentioned it on another post but I had a 2008 IS250 SE as a courtesy car yesterday, and although it was in Argentino Ice which you would expect to reflect more heat than my Cadoxton Slate, because the windows only had the light factory tint it was a damn sight hotter than mine. The A/C was working overtime.

You could try a test. Keep the heated seats on all week. The next week, don't switch the heated seats on at all. You could report back the difference in mpg.

If they use energy, they use fuel. Where else would the energy come from?

The difficulty in measuring how much arises from the impossibility of keeping everything else constant while you do the measuring.

I find it tends to cool my 'man parts' rather too much for comfort!

I guess the cold air can't escape through the holes where my legs and back are, so it tends to gush out between my legs.

For me the jury's still out on whether it's actually worth having. I certainly don't run it on anything higher than position 1.

But there might be so many other variables that change during the next week!?