LarryLikesBikes

I just found a wonderful, very low mileage 2009 E350 4-matic. Car was purchased from the estate of an elderly gentleman, and has only 41,000 original miles (supported by maintenance documents).

I knew going in that the 2009 seems to have about the worse gas mileage of any E-class in the past 20 years. But I couldn't resist, given the wonderful condition of the car.

Now that we have the car, it really is getting horrendous MPG - about 18 combined city and highway! Are there any suggestions for ways to improve MPG on this model? We had a 2001 E-350 4-Matic, and it consistentaly got 24 MPG combined (and on the freeway, I sometimes would hit 30 MPG!). I see MPG ratings for newer E-classes, and they are all much higher. For some reason, the 2008 and 2009 were the absolute worse.

Is there a ECU programming change to be made to improve this?

ps2cho

Agent-A01

Unfortunately, the 4matics have the 5 speeds.

I can tell you from experience, the RWD e350 gets much better MPG.

As high as 33mpg crusing around 65MPH.

But you should be getting better mpg if you have mostly highway.

Things to check; clogged airfilters, fuel filter.

You also want to make sure it's using a correct weight Oil; wrong stuff can affect it.
Also, old worn down oil can cause slightly worse mpg; differential oil, transfer case, trans etc.

Other obvious things, worn tires or bad alignment(or even incorrect/cheap tire) can affect mpg.
Make sure brake calipers aren't sticking etc.

ECU tune for 93 octane may get you another 1 to 2 mpg.

Strigoi

If you can't deal with that gas mileage sell it and buy something else. Simple as that. Getting a tune to gain 1-2 mpg is a complete waste of money. Custom tunes aren't cheap and it will take a long time to recoup that money.

I also wouldn't compare the mileage a W211 gets compared to different E Class models as they're totally different cars. That's like me *****ing that my E63 doesn't get as good of mileage as an E350.

FWIW there was no E350 in 2001. You had to have an E320.

LarryLikesBikes

Thank you Agent A01 for your productive comments. Seeing other, not helpful and snide comments reminds me why I typically no longer post on this forum. I do wish we could try to make this forum a more friendly place to go. Again, I appreciate your civility.

PS2CHO - I believe I answered one of your questions. I bought the car, despite knowing it would not get great gas mileage, because it is an amazing, beautiful car. And why would I NOT want to make it even better by trying to improve MPG? Have you ever purchased a house because it was in a great location, was the right size or a great price (or all)? If so, did you then seek to make the house even better - perhaps even just changing the color of the room, or putting in a more efficient furnace? Or, did you sell the house rather than trying to make the improvement.

Strigoi - yes, you are right. I mis-stated the model of my 2001. Simple typo with my mind on my current 350. And, comparing a W210 with a W211 is nothing like comparing an E63 to an E350. The difference in the latter 2 cars is night and day.

In the end, I assumed there would be no easy solutions to the MPG, but thought it was worth a try. Sometimes there are common problems to certain model years that others with similar cars have experienced and can share their knowledge. I thought it was worth asking.

Thanks for your time and responses.

relinuca

My '09 E350 4Matic consistently gets 28mpg on the hwy, and about 18mpg in subn/city driving. FWIW, highway mileage is heavily influenced by cruising speed. If I drive at 65mph w/speed control, it will get 29-30mpg, but at 70mph, it drops to 28mpg. (But then who drives a M-B at 65mph?)

relinuca

kajtek1

Beside changing the car to diesel - you can always work on ECO driving.
When I was selling E320 4M wagon, I wanted to impress buyer and I managed to get 30 mpg on 20 miles drive. (drive 65 mph and use semi-trailer drag) but average mpg was about 22 on freeway, or 7 mpg on my wife 1-mile commute.
When we go on long trip, we usually drive above 80 mph. Most cars going from 70 mph to 85 mph will increase fuel consumption by 20-25%. That is quite a lot, but driving diesel I don't car much about droping from 50 mpg.

cetialpha5

You can always get worse gas mileage, but the manufacturers have tried every trick in the book to increase gas mileage so I've never actually heard of anyone that's able to increase the gas mileage beyond what the manufacturer specs. The way they did it in later years was to go from the 5 speed to the 7 speed. Then they went to direct injection. Then they went to a 4 cylinder. Other than doing things like that, there's no way to improve gas mileage. In 2006 they went to the 3.5 liter engine so yeah, 2006-2009 would be worse than earlier 3.2 liter engines. There are minor tricks you can do like low rolling resistance tires and keeping up the air pressure, but those don't add much. Sometimes I get 14-16mpg in the city, but normally it's in the 18-20 range.