gas mileage

I took your information and did a little guess work and a little fact checking. First, you have a 16 gallon tank. I figure your measurement of a tank of gas is always leaving a couple gallons in reserve. Even with the gauge on empty, it's probably 2 gallons left. This means 280 miles in 14 gallons = 20 miles per gallon. You did not indicate whether you have a 2 door, 4 door or convertible, or if you have an automatic transmission. I'm guessing you have an automatic, and that it's a 2 or 4 door. If this is the case, the government (www.fueleconomy.gov) says you should average 21-22 miles per gallon, depending on the set up. Figure on variables such as traffic, highway verses city driving, engine idling, temperature, distance driven at one time... 20 mpg would not be terribly bad. Figure also you may be able to pick up a mile or two if you change spark plugs, ignition wires and the air filter. Make sure your tires are also aired up to the proper level. Last - don't waste your money on 91 octane. You don't need it, your engine doesn't care, and you're throwing away money. There is not even a nominal benefit for you and your car using anything other than plain ol' 87 octane.