[puddleglum]

I don't think using the alternator Is a good idea either. You are right that it puts a load on the engine and that is probably the biggest reason not to use it. If it is loading the engine then it is burning more fuel. The gas you are trying to save by warming the engine faster is being burnt up from the extra load on the engine. You may even get worse mileage, don't know. As for long trips, preheating the engine is only helping for the first 5-10 minutes of driving anyway, just until it gets to operating temp. Besides, wasting fuel to save fuel never pays in my mind.