 Gasoline companies know, too, that vehicles that run on premium won't perform as well with carbon deposits, so they pack more cleaning power into their premium fuels than their regular blend. If you rotate your fuel choices around, say, every third tankful, you may find better performance and miles per gallon because you are cleaning your engine and fuel system while you drive. Just don't tell your mechanic you're trying to replace them anytime soon. With your automotive prescription, I'm Ron Anany and The Car Doctor. See you next time. I had an important job.