C'mon folks, don't fall for that "what the oil companies don't want you to know" crap. If there was a magic ingredient they could safely put in their gas to increase your mileage 25%, they would - because everyone would want to buy it and all companies really, really like products that everyone wants to buy!

But mdwyer is right about oxygenated gas - it decreases your mileage substantially in order to decrease emissions. I would not be surprised to learn that the larger quantity of fuel you need to burn to get where you're going didn't make it into the equation, since the state gets to collect more tax on the greater number of gallons of fuel you now have to buy. Good luck getting them to stop suckling on that teat.

If you want to know where you can get the "good" gas, click here or see attached. Gas grade requirements are generally county-by-county and can change from summer to winter, too.

I try to buy gas in upstate NY and in VT whenever I'm up there to take advantage of the better mileage the VX gets from conventional gas - consistently 15-20% higher than the 10% etOH gas we get in CT.