My Bullitt is stock with approximately 6000 miles on it. I have changed the oil twice (1000 and 4000 miles) using Mobil 1. This weekend I travelled 308 miles on a tank of gas and averaged 25.56 mpg!!! It was mostly open road driving averaging 60 mph. Car is completely stock. Just felt like sharing this info considering my original mileage was hovering at 20 mpg.