"Joe Silkinson Spoon" wrote in message
news
On Thu, 25 Oct 2018 21:19:46 +0100, Rod Speed
wrote:

Gym Sulkinson Fork wrote

But the power taken from the alternator
would surely be just as bad as the wind drag?

No, because of the worse efficiency of going thru the
electricity. Alternators arent anything even remotely
like 100% efficient, and neither are electric fans.

Both are putting extra strain on the engine.

Yes, but not the same extra load, particularly given
that the van is already a considerable extra drag at
anything more than very low road speeds.

I wonder if anyone has ever studied whether you should
(for fuel efficiency) open your car window when driving on a
hot day or use the cooling fan (ignoring AC for the moment).

Yes they have and the Mythbusters tested it too, but ****ed that up a
bit.

And what was the result?

Forget now, think it was that there is bugger all in it.

Brian Gaff wrote

Hang on though, to make it spin it has to have drag. If it has drag
its using fuel. Might be moor efficient then to streamline the van
and run the fan from the van electrics which is there already.