A 12 mile RT commute? That's not very far. I bet its not warming up all the way, so I second the thermostat, but do the injectors too. I just did a set on the 300, MPG's in the low 20's now, hopefully back in the high 20's soon.

My commute is 125 miles RT everyday soo, it has a good amount of time to warm up.

Hope you get you MPG trouble sorted.

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1998 Mercedes E300TD

1983 Mercedes 240D Turbo, 131bar injectors, Cosworth intercooler and 63' Ford Falcon radiator, Ardic Parking heater, Headlight wipers, Best 38.6mpg.

1973 Saab 96 Rally Car, 1.8l V4 with all the race bits