On average road trips of 80mph speeds, usually will go right around 410-420ish miles when the light comes on. I've gotten up to 450 once before and IIRC, that next fillup it took in right at 13 gallons... You do the math... Let's just say that I've gone to Dallas and back to OKC on one tank of gas... besides, the milage is always steady between 28-32mpg... Beat that Billy!!