Gas Tank

Hi,

I have a 1999 Chevy Malibu. The gas meter on it is broken so I rely on the mileage after each time I fill up, at about 28 miles/gallon for a 15 gallon tank. I normally don't fill up until about 300-320 miles, but recently I ran out of gas at 268 miles.

I was wondering if the fact that I hadn't filled up in about 1.5-2 weeks had something to do with it? Does gas quickly "evaporate" if it's in your tank for that long? I definitely am just going to try to keep a full tank as often as possible so that doesn't happen again.

I also just wanted to write to make sure that there doesn't seem to be a fuel problem within the car itself or anything like that. Obviously I know nothing about this stuff so I'm always eager to learn!

Thanks,
Nicole