I just flashed my diesel GL with a green diesel tune and have seen 2 mpg on my 12 mile round trip commute, and 5 mpg on longer highway trips, all while gaining batter throttle response, 25 hp and 65 lb ft of torque. If anything, this is helping the environment! The rolling coal crowd gives it a bad name, and im sure those pictures were all over their website. The GL's exhaust tips are very clean, no soot at all.