Hi,

the gas mileage of my 1996 E320 dropped from 21 mpg (which was already not the best) down to 17 mpg in mixed driving 35% city 65% freeway.

According to many tips from the forum I have replaced thermostat, air filter, spark plugs, ignition coils including ignition cables, O2 sensors, MAF (after cleaning the old one did not help).

On the maintenance side I've got coolant system and transmission flushed, oil change every 4000 miles with synthetic oil.

During driving I actually can see the fuel gauge move a bit after every 15 miles as if the fuel was leaking along the road but a fuel leak is not likeky because I smell no gas, even when the car is left unused several days in the garage.

Can it be leaking only when driving? I just don't what more to do now except taking the car to the dealership or an indy.

Any suggestion would be appreciated.

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1996 E320 since 1/16/08, 171K miles as of Feb 2011

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1989 300CE - R.I.P. Dec 29 2007
Other MBs (sold): 1992 300E-24 - 1979 350SLC - 1984 230E - 1990 300CE