what is the best fuel additive that will increase my gas mileage?
Use good quality gasoline (I prefer Shell or BP). I also occasionally use Chevron Techron Fuel Injector Cleaner about every 10-15,000 miles. Other than that the best thing you can do is maintain your car overall and change your driving habits as others have mentioned. Keep the correct tire pressure, change your air filter regularly, buy quality gasoline and drive in a reasonable manner and that will get you the best gas mileage. There are no quick fixes.
Its not a fuel additive, its called common sense and reasonable driving habits. Even better, because it doesn't cost you anything, and it saves you money.
I will answer this question specifically, first let me say most if not all additives can do more harm than good to your car,most cars today recommends not using any additives they can mess with your oxygen sensor and or injectors,most cars today are so sensitive and some people wonder why the oxygen sensor light comes on so often, it can even detect bad gas which is typical these days, and with the gas prices coming out today so will a flood of gasoline VOO DOO claiming to work magic also the typical brand names that are eye catchers i wont use names but average around $9 to $12 bucks that is roughly two gallons of gasoline and will get you much further that a few ounces of faith in a bottle
