dtrentr

I'll be on the road tomorrow for 400miles in my E-320 Bluetec. Will be mostly 60-70 mph, all flat, and will have the a/c on. Will report back on Wednesday my mileage. Still just 4200 miles on the car. Will throw in a couple of 3500 rpm hard throttles and see if that blow any dust out (seems kind of counter-intuitive).

Talbot

I did exactly that, as noted in my original post (which seems to be somewhat obscured now by exhaust talk). The only difference in what you suggested is that I did it at 75mph and not 65mph.

Ashkan's C43

I thought that removeing the erg and alda would improve mpg? Or would removing the erg and having that plate put in improve mpg and removing alda improve hp?

Ashkan's C43

congrats on the 31 mpg avg, I could only imagine how much higher your mpg would have been if it was 65% highway instead, kudos!

Alan Smithee

There is a big difference between consumption at 65 MPH and 75 MPH. In my CDI, 65 MPH is 36-37 MPG, while 75 MPH is 32-33 MPG. I think this is why it was suggested you try the lower speed before being concerned your mileage is low.

Talbot

I'll try it, but going 65 on interstates around here is a fine way to get killed.

The other Bluetec owner I was comparing notes with stated his results at 75, so I was just trying to match his reference data as much as possible.

I guess the guys running in the Paris-to-Beijing run were all runing at 45-65mph or so to get the mileage they reportedly got.

Alan Smithee

Yes, and probably escorted so as not to have to stop and accelerate as the rest of us have to in our daily routine.

Talbot

http://www.designnews.com/article/CA6403301.html

http://www.greencar.com/index.cfm?co...D=172&show=all

http://www.popularmechanics.com/blog...s/4200498.html

I'm not getting anything close to what's stated that was obtained in real-world testing mentioned in the above articles - at ANY speed.
(the last one includes driving at 130mph and travel through cities for an average of 25-30mpg).

Alan Smithee

That's not real-world testing. It is a Mercedes-Benz publicity stunt.

Between the three articles they mention betweeen 25 and 43 MPG. That's a huge spread...certianly you're getting something in between.

Talbot

My average is 25. Do you call that in between? Why is it so implausable that I'm getting something out of spec?

JRAMGV8

I have read positive and negative on the fuel mileage but Im sure this car can range 36 or more on hwy. This is a car that I am leaning towards to get just because of the mileage and also its a Mercedes . Too bad this is the only Diesel vehicle on a 4 door model sedan in the U.S. An S-Class bluetech would be awesome!!!

Alan Smithee

25 MPG for mixed driving of city traffic and 70+ MPH cruising is not unreasonable. The high figures quoted by MB press materials and the EPA are for very conservative driving with very few stops at 40-60 MPH; if you are outside of that range on either side, consumption will drop.

As has been suggested, try re-setting the computer on a flat surface with no wind at 60-65 MPH for a few miles and see what it reads. If it says 25 MPG, by all means bring it in.

The reason it is "so implausible" that your car is "out of spec" is because (a) the driving you described from your first post is not optimal for mileage, so you will not get optimal mileage, and (b) this isn't 1968 with carbureted motors that need the jets and timing set just right for maxiumum performance...it is completely computer controlled, and if any of the many sensors detect anything "out of spec", you'll get a 'check engine' light.

Talbot

I will be traveling this weekend to eastern GA. Once I get below the fall line (where it becomes very flat), I will test various speeds and report my results.

I have done this before, but at the time I didn't make specific notes on my findings.

Incidentally, I suppose there are other things that could impact mileage which don't involve the engine or sensors. Rolling resistance and transmission adaptation are a couple that come to mind off the top of my head.

Again, back to my first post, I already 'brought it in', and all they were interested in doing is pointing to the 'your mileage may vary' section on another Bluetec's sticker. Hell, they didn't even adjust the tire pressure for the tire rotation, so how can I give them too much credit for anything really?

DslBnz

Yes.

The main thing removing the EGR will do is keep your intake path clean from oily soot. The engine can breathe easier with this disabled in some way or another. Just make sure that valve is closed if you choose to leave your EGR in place.

Removing the ALDA completely will allow you to provide full fuel enrichment off idle even before turbo boost builds to accommodate the increase in fuel flow. Your right foot controls the enrichment.

IOW, if you stomp to go-pedal from a dead stop too often, economy will suffer accordingly and a black cloud will spew out from your tailpipes just before boost levels rise. Approximately 2 mpg loss, on average, this way.

Untertürkheim

It is confusing to think that relatively small increases in speed have resulted in such large declined in fuel economy. These cars should certainly not see any fuel economy drop off as low as 75-80 mph considering the highway fuel economy for the European consumtion test is done at 120km/h (75mph). This would lead me to believe that one could drive these cars up to 85 or 90mph (130-135 km/h) before significant losses are seen. The most important thing to remember is that A/C use and city driving will drastically decrease your fuel economy. Try using the climate conrrol in E/C mode and keeping the revs down on acceleration. Maybe also try to get an economy measurement of strictly highway sans AC.

harkgar

What can be done in the 2005-2006 CDi to eliminate the EGR and Alda (if present) without triggering the CEL (check engine light)? Would this have any beneficial effects on performance and economy?

I know in the older muscle cars (V-8 gasoline engines) with carburettors tuners can put in a replacement engine oil filler cap which vents directly into the engine bay. In newer MB cars this cannot be done for some reason.

harkgar

Part of the joy of owning a new MB diesel is its torque, speed, refinement and luxury. If mileage is paramount buy a Jetta 1.9 liter TDi with a 5 speed manual transmission. You cannot get less than 40 mpg city and 50 mpg highway no matter how hard you try.

Enjoy the Bluetec. Forget the mileage.

dtrentr

On the run yesterday, temp @ 88F, tire pressure to specs, A/C on (if there's an economy mode on a 2007 Bluetec, I don't know where the button is), I got 33.4 going 65 on the two lanes,and 34.3 going 70 on the four lanes, road flat as a tabletop. EPA estimates are now 26/35, so I have a ways to go to get to that on the highway. I am keeping in mind that I only have 4.6K, so hope for some improvement down the road.

Alan Smithee

It's not a safe assumption that both US- and Euro-spec cars have the same gearing.

Talbot

Well, that's my thought exactly. I'll do my testing with and without AC, too.

Talbot

I can certainly understand why you've gotten the impression that I care about the economy. It was just a curiousity, and I brought it up here originally just for conversation and to see if anyone would say, "Hey, I've seen that, have them look at x." Other than that, I've lost neither sleep nor enjoyment over the whole thing.

Untertürkheim

In this case I believe they do.

Untertürkheim

I believe there is a button on the climate control that says A/C Off, so that you can use the climate control without the compressor turning on.

harkgar

Talbot,

I was not saying you are stingy on diesel. I owned and drove a 1999 VW
Jetta TDi and found that I no matter how hard I tried I could not get the mileage under 40 mpg. The car was bone stock for a couple of years after which I put in an Upsolute chip. 1999 was the last year the car can accept a "plug and play" chip.

Compared with my 2006 common rail straight six the VW was agricultural but I bought it for my sons to make sure they do not speed like me.

NickIndy

I have an '05 E320CDI which is rated 27 city, 37 highway. I drove from here (Indiana) to Hilton Head SC on 1 tank of fuel (100% interstate) and it was October so the AC was switched off most of the way. The trip computer only gave me 33mpg or so. Needless to say, in 3 years and 48k miles I've never seen anywhere close to 37mpg at anytime on any type of driving. Average has been closer to 29-30mpg. Maybe the guy you're comparing with just got lucky with exceptional mileage and you're seeing somewhat closer to normal?