In my records it was averaging 26-27 mpg, so roughly 2.5 times better mileage. It had gone down the last 7 months. Most likely indicating the beginning of the demise. Bought the Impala shortly after the truck so I had both for about 7 years. Truck put on 70,000 miles. Car put 180,000 miles. Had my Cherokee there for a few of those years that we put about 50,000 miles on. Without the Jeep those miles would have been on the truck. At 20 mpg vs 10 mpg the Jeep more than paid for itself by keeping unnecessary miles off the truck. My Saturn is now the vehicle keeping the miles off the truck. Well, not quite as I'm short one Impala right now so my wife is temporarily driving the truck to work.