I'm worried that there is a leak in my fuel tank. When I bought the car two months ago, I was getting 270-300 miles on a single tank of gas. Now, I'm getting an average of 200 miles on a tank of gas. My driving is rather consistent, and I drive on the freeway for the most part. When I'm not rushing, I drive between 65-70 mph. I do drive a bit faster when I'm running late. While I'm driving, I don't notice a significant change on my fuel gauge. But when I turn the car on, there is usually a noticeable drop on the fuel gauge.

I can't think of an explanation for the significant drop in fuel efficiency. I'm wondering if there is some routine maintenance that hasn't been done or if there is a leak in my fuel tank or elsewhere that would cause this drop.