Shadow5501

Existing fool economy discussions are mostly sedan owners, I want to start one for the wagons. Am curious what owners of w203 wagons see as typical fuel economy numbers.

Here's my story. I bought a nicely kept, 65K mile 2004 C240 wagon earlier in 2011. It's useful for carrying around my dogs, bicycles, etc. This is my, uh, 10th Mercedes, give or take one. It's up to date on all maintenance and runs properly.

My question is the fuel economy is surprisingly low, given that it is not a large car, and has a relatively small, low powered engine. Anecdotally, I typically get about 20MPG in my suburban/urban driving, with a mix of surface streets and a bit of urban highway. I recently took a 400+ mile road trip from Dallas to points south. The route out and back was 200 miles of highway, about 50 miles @ 60MPH limit, the remainder at 70MPH limit. Driving mostly at the speed limit, and never more than 5MPH over, I got 24.1MPG on the way down, and 24.8MPG coming home. There were no traffic jams or stops, my average speed each way was about 63MPH per the trip computer. I'll note it was very hot - up to 108F at times, so the a/c was working hard.

This seems awfully low for an aerodynamic, small car with a 2.6L engine. As a comparison, my last MB wagon was a 210 E320. Quite a bit larger, with a larger variant of the same engine/transmission family. It returned the same or better fuel economy in the city, and quite a bit better highway. That car typically returned 28MPG on highway trips, and occasionally broke 30MPG under favorable conditions.

I'm wondering why the 203 seems to be less fuel efficient than the 210? What do you-all see from your 203 wagons?

glocati

My 240 wagon gets 20 combined and ~26 + freeway. The 2.6 is just not that fuel efficient.. Do you run premium or mid grade fuel?

euromedic

2002 C320 Wagon. Used to get 23 MPG on average, but down to about 21.5 now 113K miles, 100K fluid changes/new spark plugs/5W30 Mobil 1 oil. Agree that it should be a bit better, but I think it is simply the added weight compared to the sedans that dumps the fuel economy. Aside from that, love the car I am thinking of taking the Evosport pulley route to see if that will improve MPG a bit, certainly would improve low end pickup from what i read here

It certainly is a hoss when fully loaded with luggage and trailer

Moviela

Isn't your car naturally aspirated? Would a pulley change anything? I may be wrong, but aren't pulleys used to spin the supercharger faster and increase boost?

Shadow5501

Thanks guys. Sounds like I'm in the expected neighborhood, fuel economy wise. I know wagons are generally at a disadvatage relative to sedans because they are both heavier and (usually) less aerodynamic.

One thing I noticed is that MB created the 2.6L by reducing only the stroke relative to the 3.2L engine. They share the same bore, and presumably bore centers, etc. I wonder if the oversquare, short stroke 2.6L engine is less efficient at converting the potential energy in gasoline to mechanical work?

Shadow5501

Yes, it is naturally aspirated. The pullies "underdrive" the water pump, alternator, a/c compressor, etc. reducing the power losses to these accessories. This increases the power available at the wheels, and reduces fuel consumption. I don't know how significant an impact this can have. My guess is it's pretty darn small. And of course the tradeoff is that you have less electricity, less air conditioning, etc. available...

LILBENZ230

Not that this has anything to do with your fuel economy, per se, but I don't believe your M1 5W30 meets the specs for your car. IIRC, that's a 229.51 oil for a diesel. You need 229.5 0W40 or the like. They are not cross compatible.

Carsy

Some wagons in the past have a shorter diff ratio to enable them to carry the extra weight
Have a look at your specs.

hanknum

My wife usually averages about 25mpg...I usually average around 22. I did the Eurocharge ECU tune and power increase and especially throttle response was better. We are also getting around 2mpg more, each. When my wife's cruising on the freeway she can be in the high 20's.

Also, I think going 0-30 or 0-40 oil made a difference when I tried it a while back.