[SBTanMan]

Most new cars formulated for premium can adjust to regular gas, but at the cost of performance and possibly the life of the engine. Since the Mz3 is made for regular and doesn't have an electronic knock sensor, it will not gain any performance nor MPG from premium. On the other hand, if you put premium in a car with an electronic knock sensor, you might gain a little performance or fuel economy (try it on a Honda Accord V6 or 4 cylinder as an example). Oh, and this topic is pretty similar to a previous one that got moved to Powerplant, so don't get too offended if it gets moved and locked with a link to the other topic.