Internet says 18.8 gallons. Today I was on empty (fuel range 5 miles)and was only able to put 13 gallons of gas in my tank. That seems like a small tank for an SUV. My previous Chevy Avalanche had a 30-gallon tank. I looked in the manual and can't find where it lists the size. Does anyone have this information? I'm wondering if my sensors are faulty. If I could only put in 13 gallons and it's showing a full tank, then something is not right..... Was I really on empty?