I have a S320 with same engine my mileage when trying is 28.5 hwy.Of course 20 in city.But my car is heavier.The engines are tough,what I have read on E Class is sensor problems sometimes.Like crank and cam sensors,and various things inside.But are replaceable.If you can do you own labor you can save a bundle.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran, deutschland deutschland uber alles uber alles in der welt