We bought our 05 chev new. Tested the dic for fuel used and mileage against math. It was the same. 06 we towed to branson and when driving I fill the inbed tank to overfill almost. Set the fuel used and later looked to see 44 gals used so at the time it hit 45 I switched tanks. filled and same over filled almost. Looked at the pump and 45 gallons exactly. But in 09 the speedometer had a problem and after the fix it changed perfect to close enough. Now I really just drive and fill when needed. Truck is old and same for me.
chevman