My Denali has a modified 6.0 so it is now designed for premium. I get anywhere deom 10-15 mpg depending on how heavy my foot is. My last tank was almost $70, and it will probably be over that when I fill up tomorrow since I am getting below a 1/4 tank. It'* just the price I need to pay to play.
hmm, i was thinking...i wonder if your gas tank was ever replaced before you bought the car or before Todd even, you know? Maybe an aftermarket tank that is a few more gallons than the stock tank? It was a wisconsin car..so maybe salt, but then again, lots of places have salt..but still....who knows?