I found the perfect site to find out. Gasaroo tracks real-world gas mileage that people are getting. This means you can enter in your car and find out what mileage other owners of the same make model and year are getting. They also have a fantastic tag line: “we want to know when you’ve got gas.”
It turns out that the average mpg is 23.40 so there’s room for improvement.
I’ve considered learning more about hypermiling. It seems like a good idea but I like my A/C on hot days and I value my life too much to draft 10 feet behind large trucks.