brent eb02

i bought a 06 e320 cdi and i only seem to get about 25 mpg with city and highway mixed driving...
i expected much better

anyone have any suggestions what could be wrong?

mtrevelino

I only had my 06 for about 1 1/2 years. The worst it got was 24 and the best was 34. I would take it on the highway and reset the mpg while cruising at 70. It should come back in the 30's. If not, I do not know what could be the problem.
Mike T.

2slowcdi

EPA was 27 city 37 Hwy with tires that where low roll resistance with out AC going.

Fuel is the next big thing always go to a place that moves the diesel. I seem to get better mileage from Shell truck stops.

I drove about 1400 miles over July 4 and my avg was 35 mpg it was with AC on all the time that about 150 miles in town.
Speed was around 75 mph in New Mexico and 70 mph in Texas.

I use a cetane boost in every tank.

My in town mileage is around 25 mpg.
The mileage gauge shows better most of the time upwards a 2 mpg.

My car is in the shop " I was hit" and the car that I'm in is a Chev Malibu
with a 4 cyl motor and the mileage is the same as my CDI with out the power or the other Benz goodies.

My last car was a 2003 VW TDI diesel and it would get 50 mpg with everything just right , it was easy to see what changed the mileage with it as a little things would show,.

I hope this helps

mtrevelino

Let me clarify my previous posting. The 34 mg was combined city/highway driving. While driving down I-95 in Virginia and resetting the computer, my cdi did average 38 mpg, but as soon as I pulled off the highway into city traffic, the average mpg goes down. I keep a Excel spreadsheet of fuel costs which includes mpg per tank of fuel.
Mike T.

ImInPA

Your experience is totally normal. This occurs with gas engines too. Having just had a gasser as a loaner for a few days I can telll you that in the city, where my E350 Bluetec gets 25, the gasser is only getting 14. It is all realative.There is nothing "poor" about a 4000 lb. car that is getting 38 mpg on the Hwy. That is phenomenal.

edwinwalke

My 06 E320 CDI routinely gets 40-41 MPG on straight interstate driving if I keep it at 65MPH. My average with mixed city and some interstate is 32 and that is checking it the old way with miles driven divided by gallons use. My trip computer shows an average of 31 over the past 10K miles which is mostly mixed city and interstate.

Pierre Louis

These cars use a lot of oxygen and thus rely on the air filter. Did you check it or replace it lately? Mine just gained a couple of mpg's by getting a fresh oil change and new air filter. Going strong at 199,640 miles. Daughter just got 39 mpg at a steady 70 mph from GA to OH and back!

PL

Carsy

Check how easily the car rolls , are the brakes binding ?

Your driving style can make a huge difference. For improved consumption :- no heavy acceleration or braking,anticipate traffic lights, drive slower ( get up 5 minutes earlier !), use A/C less, clean out heavy objects in boot, a few extra pounds in tyres, have car tuned to perfection( including as above) air filter .

Good luck.

Lancelot

The oxygen part is correct. I'm in Europe and I'm assuming your '06 still has the straight-six CDI as in my W210. How many Miles are on the car? It's a good chance your EGR valve and inlet manifold need cleaning. Mine were clogged with a thick gunk of sooth and oil after 285,000km (177,000miles) thus restricting airflow for about 25%. This manifested in thick black unburned diesel fumes in hot weather...

See this post:
cleaned-my-egr-traject-what-mess!

brent eb02

thanks guys i will look into the egr and air filter

harkgar

I regularly get 26 mpg City and 40 mpg highway and I have 100,500 km on my E320 CDi.

harkgar

Hey Lancelot: please teach me how to get rid of my EGR!

Pierre Louis

Say hello to Guinevere for me!

harkgar

King Arthur will go after you with his sword.