Premium or Regular Gas?

Lower octane costs less, but should you use it? Most modern cars that call for premium fuel can run on regular gasoline without knocking or any long-term penalty. Technically, this makes the car less efficient, but not to a degree that negates the cost savings from the cheaper fuel grade. NOTE: This is true of cars for which premium is recommended, not required. If in doubt, look for terms such as "for best performance" and "recommended" as opposed to "only" or "required." If your car has a turbocharger or supercharger, you probably should stick with premium fuel. Of course, if your car calls for regular gasoline, there's no reason to run it on anything higher in octane.