How many miles do you get on a full tank?

My gas gauge doesn't work right but I found an average of 25mpg. That's with a paper route and a lot of idle time. That's after a good oil change etc. Before that I was getting gas mileage so bad peta would cry. Regular driving I could probably attain 30mpg. I have the 3100 V6 too. About 375 miles a tank.