x.x forreals man they starting going up again rofl BS!!

 

If I was really lucky with mostly highway driving I could get 300 miles a tank, but the light would have to be on for a little while. The most I've ever gotten out of a tank was about 410 miles, 98% highway at an average speed of 80-85mph with a few bursts to 95-100.

The car learns your driving patterns. If you spend alot of time on surface streets "hooning" it, the car will train itself to have a little better throttle response and punch. Spend all your time on the interstate (like the aforementioned roadtrip), throttle response dims a bit and the car go further on gas.

The same seems to be true for the gas gauge. The light comes on alot sooner in the first scenario than the second one.

 

It's called a reserve, most cars usually have 2 gallons remaining after the light comes on. It's an aid for those who are careless and helps avoid getting stuck on the side of the road (for most at least)....

 

I'm not trying to be a jerk here, but seriously man, this is not how to gauge mileage as many others have stated. Based on what you said above, you got 9 MPG on 90% highway driving. I call B.S. 9 mi/gal x 12 gal = 108 miles Even based on your original post #'s, something's not right if you're truly driving below 2K rpms and 65 mph on the highway.

As others have said, fill your car all the way up then reset your odometer. Then try to drive primarily highway miles, and keep the revs low and stay within 10 mph of the speed limit. You should probably try to drive at LEAST until you're at 3/4 of a tank or more if you can. Then go back to the same gas station using the same gas dispenser, fill it back up the same way. Then do the math using the actual # of gallons the dispenser says (they even round to the nearest thousandth of a gallon!). Let us know man!