Gas mileage question
Hi, I have a few questions concerning gas mileage. Mainly what happens to it as you add performance parts to the car. I have heard lots of different stuff, and I don't know who to believe. It seems that generally the more hp an engine has, the worse the mpg. (Compare Lancer ES to Lancer Evolution, both 2.0L 4 cyclinders.) But people have told me that if you add an intake and better exhaust, you will get better gas mileage and more hp. I remember seeing an add in a newspaper for putting dual exhausts on trucks, said adds up to 35hp and 5 mpg.
What about turbos and superchargers? They force more air and fuel into each cyclinder right? This would mean they burn more fuel and thus get worse gas mileage wouldn't it? But then alot of my friends claim that turbochargers actually save gas... If you have a manual boost controller on a turbocharged car, would this mean that you can "turn off" the turbo when just driving from point A to point B, and get the same gas mileage you would without the turbo, and only turn on the boost when you want to go fast?