i have a 1990 mercedes 300e. 3.2 litre inline 6. 119000 miles
i also have terrible fuel economy, i am getting around 13.5 mpg-i have even started using premium fuel, but this has made no noticable difference.
the car was previously owned by my mechanics, is in good condition, new radiator and exaust.
i drive this car so easily, rarly bringing RPMs over 3000, so i should be getting some good fuel economy despite me doing city drving.
the only thing i can thing of is maybe an air filter?? i dunno how to open it up and look to see if its dirty. any suggestions would be greatly appreciated.

 

You will not get good mileage on short trips, stop and go city driving despite you driving method.

This may be you best mileage with city driving. Fill it up and take a trip on the hiway to see what the mileage will be.

 

i was gettin about 15mpg on the highway, i drove about 45 miles, and then filled up again and thats what i got. i am hopeful it is the air filter, sure its the airfilter. someone please help me. i am spending sooooo much money on gasss. please help!!!!!!!

 

When your getting bad gas mileage first thing to look at is your "Oxygen Sensor". Probably will cost $30 to $40 bucks depending on the vehicle.

 

This is cheap but can make a diffreance tire pressure should be checked.It sounds simple but it does matter.
Then a tune up will not hurt.

 

the car was previously owned by my mechanics, is in good condition, new radiator and exaust.

This is just a thought, but why are you not asking the mechanics who the car used to belong to? They would have a better insite on what is or what has been wrong with the car in the past.

If for some reason you can not get in touch with them, I would ask, if the performance has suffered, and if so, you can check to see if all cylendars are firing, possibly a fouled spark plug or bad wire, as far as the air filter goes, you could go by an auto parts store (Autozone in Indiana is great), they should install the air filter for free if you purchase it from them.

Hope this helps.