Bad gas mileage? Whats the problem?

[soydios]

A lot of it depends on driving style and usage.
Fast driving and passing a lot on the freeway lowers your fuel economy.
Using the air conditioning lowers your fuel economy.
When you are sitting in stop and go traffic, you are getting exactly zero miles per gallon.
Simply put, if the accelerator pedal ever goes more than halfway down, you're driving pretty agressively. You'll still get to the same speed, it'll just take a bit longer.

And use regular fuel. The engine computer can compensate for it. Your miles per gallon will go down (less energy per gallon, duh), but the lower price of the cheaper fuel will more than make up for it.