Preheating the gas is way less effective than preheating the air, as the air weighs so much more than the tiny fraction of fuel it burns. Unless you heat the fuel a lot, but that is both cumbersome and dangerous. I think much of the heat would get lost in the injectors btw.
Checked the revs on my car this morning. 9 degrees Celsius, 1300 RPM, just 28% load. So that would be some 5.3 Watt needed per degree rise in temperature. 150 Watt would raise it to 35 degrees Celsius! That is enough to make a difference.
It will rev a bit higher with higher load when it is freezing, but still it would have an effect.
I'll go look for some 150W heater to hook up, manually switched at first.
I feel my first ever seriously conducted ABA testing coming up
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2011 Honda Insight + HID, LEDs, tiny PV panel, extra brake pad return springs, neutral wheel alignment, 44/42 PSI (air), PHEV light (inop), tightened wheel nut.
lifetime FE over 0.2 Gigameter or 0.13 Megamile.
For confirmation go to people just like you.
For education go to people unlike yourself.