Calling all BLUETEC owners!

[alcarey]

I would be very interested in hearing from other owners of the 2007 BLUETEC about their fuel economy experience.

My 2007 BLUETEC now has a little over 4000 miles on it and the fuel economy has been remarkably steady at about 30.5 mpg. I keep a spreadsheet record, logging accumulated miles, fuel consumed, tank-to-tank mpg and cumulative mpg. With few exceptions, I always refuel at the same station and pump (Flying J).

Most of the miles driven are highway (Interstate), with relatively little city driving

I am concerned on two counts. First, my BLUETEC fuel economy falls substantially below the EPA Highway Estimate (37 mpg), and, second, it is only slightly better than my experience with my 98 E300 Turbodiesel. I expected better economy.

[lkchris]

Well, you're getting same economy but with LOTS more power and acceleration, which really means you're ahead.

On our '06 I've only ever used speedo calculations and on long (200 mile plus) highway trips we get 38 and normal around-town running registers 21-24. Recent highway trip with high winds created 32.

Can't think of any reason why Bluetec would be worse than immediately previous models and would expect it to be better in fact.

[alcarey]

EPA Estimates for the BLUETEC are 26 mpg (City); 37 mpg (Highway).

Fuel economy quoted on the MB/Germany website for the E320CDI:

City (innerorts) 22.8 22.2mpg
Hwy (ausserorts) 42.0 39.0
Combined 32.2 30.95

Considering that the German numbers are based on actual vehicle driving tests per EU regulations and that the EPA numbers are based on carbon balance calculations of emission test results, I guess it could be argued that my car's fuel economy is well within specs.

Aside from fuel economy, everything about the car is terrific. As you've said, acceleration, speed, and NVH (noise, vibration and harshness) are all you could ask for from any car. In short, it's a dream to drive. It's a great driving machine, to borrow the BMW line.

Al Carey
Columbus, IN
98 E300 Turbodiesel (179K miles)
07 E320 BLUETEC (4K miles)

[Drivbiwire]

Modern diesel typically do not see maximum fuel economy until around 60,000 miles. A brand new engine (diesel) has the lowest compression pressures in it's life (aside from an engine with 2,000,000 miles on it).

As the cylinders and rings seat you will see a slow and measured increase in fuel economy. It just takes time.

Be firm with the gas pedal (relative to the gas energy in the cylinder). Don't lug the engine around, a couple times a day floor it, let it breathe and get it up on boost.

Diesel efficiency is solely related to the amount of pressure generated on each compression stroke. By the time you get to 60K the cylinder pressures will be very close to the maximum they will ever see.

Patience...

DB

[alcarey]

I have to set the record straight.

Although the new car window sticker on my BLUETEC showed the EPA mileage estimates as 26 City and 37 Highway, the official EPA Fuel Economy Guide for 2007 vehicles rates the BLUETEC at 26 City and 35 Highway.

For comparison, the 2006 E320 CDI figures, per the 2006 EPA Guide, were 27 City and 37 Highway, so it's clear that the BLUETEC is actually a step backward in fuel economy.

I believe MB chose to sacrifice a bit of fuel economy in an attempt to qualify the BLUETEC as a 50-State car - retarding injection timing will reduce both fuel economy and NOx emissions. Unfortunately for MB, their attempt to achieve a 50-State car failed.

If my guess is correct, future BLUETEC cars, which will probably require the use of AdBlue urea solution to control NOx, will employ injection timing optimized for fuel economy, since NOx will have been effectively eliminated by the SCR/AdBlue system.

It will be interesting to see how this all plays out.

[lkchris]

You need to understand that between 2006 and 2007 EPA changed the way it tests and calculates fuel economy figures.

It's ludicrous to call the Bluetec a step backwards.

[alcarey]

You're right. EPA did change the way they "adjusted" their test results to better reflect actual usage. In 2006, test results (both City and Highway) were reduced 15%. In 2007, test results were reduced 10% for City and 22% for Highway.

Using these "adjustments," it could be inferred that the unadjusted EPA test results for the 2006 E320CDI were 31.8 City and 43.5 Highway.

Similarly, using the 2007 "adjustments," the unadjusted EPA test results for the BLUETEC were 28.9 City and 44.9 Highway.

As far as I know, the actual EPA test procedures have been the same for quite a while. Fuel economy values are derived from carbon balance calculations of emission test results.

[Tuco]

Sorry to hear that your economy is not what you were predicting. We have a 3.0 CRD too and it has incredible accleration for the size of the engine. Some of us who are okay with a little less power and more interested in economy would like to see a compromise, but I guess the market drives these things.

As an owner of a 2007 Jeep Grand Cherokee that uses the same engine (but without bluetec) we were wondering how to break in this CRD and how long to break in. I certainly dont want to rob this thread and will start a new one if I could figure out where to post. Hope you MB folks dont mind a Jeep intruder :).

We hear a lot about using hard accelerations and not to drive with a light foot. Im okay with this, but we really want to drive with the best economy we can acheive. So how long should we be driving it "hard?" Also, does it help to do a lot of compression braking?

Could someone explain why driving the rig like we stole it is good for the break in?

Thanks!

PS our economy is around low 20's for city but have not done enough driving to really say for sure ( only has 500 miles on it). Im convinced if they had put in a 6 or 7 speed tranny instead of the 5 speed we could squeeze a couple more mpg.

[daddy long legs]

My average is 26, mostly city. Highway gives me around 34. I'm very pleased with this. The car is a solid 10 IMO. The Bluetec replaced a 2006 BMW 530i which is difficult to beat in terms of all around performance, and there are some things about the 530 that BMW does best. Being a turbodiesel, the BT wins hands down in terms of mileage. Can't slight it on anything. The perfect luxury automobile..... for now. I've only had it a month. The car was given kudos by JD Power for initial quality. I'll hold off on a final opinion for the first 10 to 15k. By then I should know if it's a keeper.

[Skid Row Joe]

It's good to know that the new diesels consistently aren't getting the quoted mileage figures, any better than the older 1998 & 1999 E300TDs are.. I have read elsewhere of the Bluetec getting 42 mpg.. I knew that was total fantasy.

My '99 E300TD has never gotten any better than 32 mpg, at any speed, under any weather conditions. The HWY average is a solid 30 mpg. --No better than the '83 300SD. CITY, is not the advertised 26 mpg, more like 22 mpg. Each and every tank fill-up is calculated and logged for miles per gallon. No guesswork, or fudging the numbers.. The window sticker said 36 mpg HWY --No way, ain't gonna happen.

I rarely use the A/C, even when 95' to 100' every day in the Summer, so that doesn't even enter into the mpg picture..

There is creedence to a diesel not getting it's optimum mpg until 60K, it's just nothing to write home about........2.0% improvement on my '99 E300TD, is nothing to get excited about.

[DieselDave]

I own a 95 E300D, a 97 E300D and a 05 E320cdi.

I experience the as-advertised fuel economy with the E320cdi - a little 225 mile trip I took earlier this week (mostly highway) showed 37.5 mpg with cruise set on 70mph, and running the A/C.

I have a 32 mile each way daily commute, again, mostly highway. My door-to-door mpg is usually between 35 and 37 mpg.

Even errand running, stop and start driving around town, mixed highway/city driving calculated when I fill up is around 30 mpg.

[lkchris]

The Bluetec replaced a 2006 BMW 530i which is difficult to beat in terms of all around performance, and there are some things about the 530 that BMW does best.

Torque sure isn't one of them.

530i requires a downshift at the slightest hint of highway upslope.

Never on the E320CDI.

[daddy long legs]

It's good to know that the new diesels consistently aren't getting the quoted mileage figures, any better than the older 1998 & 1999 E300TDs are.. I have read elsewhere of the Bluetec getting 42 mpg.. I knew that was total fantasy.

My '99 E300TD has never gotten any better than 32 mpg, at any speed, under any weather conditions. The HWY average is a solid 30 mpg. --No better than the '83 300SD. CITY, is not the advertised 26 mpg, more like 22 mpg. Each and every tank fill-up is calculated and logged for miles per gallon. No guesswork, or fudging the numbers.. The window sticker said 36 mpg HWY --No way, ain't gonna happen.

I rarely use the A/C, even when 95' to 100' every day in the Summer, so that doesn't even enter into the mpg picture..

There is creedence to a diesel not getting it's optimum mpg until 60K, it's just nothing to write home about........2.0% improvement on my '99 E300TD, is nothing to get excited about.


I believe I'm getting at least the mileage that was shown on the MSRP Sticker. If I recall correctly, it said 23 city, 34 highway. The E-350 gasoline model has a sticker showing 16/23 if I recall correctly. Diesel mileage is supposed to be around 30% better than the equivalent gas model. I'd say I'm getting at least that percentage.

The 05 and 06 CDI models seem to get better mileage than the 07 and 08 Bluetecs, I would guess because of the stricter emissions requirements on the 2007 and 2008 models, and possibly the requirement for ULSD rather than LSD. You lose a little energy with the extra sulfur reduction. I would say 90% of the differences in our mileage is due to differences in our driving habits and varying mix of city/highway driving. All I know is I'm very pleased with the mileage I'm getting. The only other diesel I've owned was a 198x VW Rabbit diesel. That thing was such a slug even tractor trailer rigs were passing me. Nothing like the new diesels.

[Skid Row Joe]

I have had my own suspicions that the 05 & 06 E320CDIs were MPG winners.
I am tempted to buy a pre-owned CDI, and sell my E300TD. I just don't need one.

[daddy long legs]

I have had my own suspicions that the 05 & 06 E320CDIs were MPG winners.
I am tempted to buy a pre-owned CDI, and sell my E300TD. I just don't need one.

You may want to keep in mind that the diesels which were designed for higher sulfer content may not, in the long term, hold up the way they would with the higher sulfur content. George Murphy wrote an article in a recent Star edition which may offer a solution to solving this issue with the diesels designed for higher sulfur fuel.

[lkchris]

You may want to keep in mind that the diesels which were designed for higher sulfer content may not, in the long term, hold up the way they would with the higher sulfur content. George Murphy wrote an article in a recent Star edition which may offer a solution to solving this issue with the diesels designed for higher sulfur fuel.

This concept is flawed because European diesel fuel has been ultra low sulphur for many years prior to the USA changeover. The OM648 WAS NOT designed for higher sulphur fuel.

Nothing George wrote applies to the E320CDI nor the Bluetecs. At least not with accuracy.

Plus, sulphur in diesel is just a contaminent and is not something needed. The refining process to remove it does reduce lubricity, but this is returned by additions later in the process to again achieve the required lubricity. No further additives are required.

Given that lubricity is the same for both LSD and ULSD it can easily be said that both the I6 and V6 diesels will use them equally successfully. In fact, the ONLY reason the newer car requires ULSD is because the sulphur will poison the particulate filters added to the exhaust system. The same filters could theoretically be added to the older cars and then they'd require the new fuel, too. It's nothing to do, that is, with engine design, but rather with exhaust aftertreatment components.

Just as an FYI, the newer cars also require different motor oil for the same reason, i.e. protection of the particulate filter. This oil is fine for the older cars and is very likely what you'll get at a dealer in any event. A sticker under the hood, incidentally, cautions against even adding oil between changes using the wrong stuff.

[daddy long legs]

This concept is flawed because European diesel fuel has been ultra low sulphur for many years prior to the USA changeover. The OM648 WAS NOT designed for higher sulphur fuel.

Nothing George wrote applies to the E320CDI nor the Bluetecs. At least not with accuracy.

Plus, sulphur in diesel is just a contaminent and is not something needed. The refining process to remove it does reduce lubricity, but this is returned by additions later in the process to again achieve the required lubricity. No further additives are required.

Given that lubricity is the same for both LSD and ULSD it can easily be said that both the I6 and V6 diesels will use them equally successfully. In fact, the ONLY reason the newer car requires ULSD is because the sulphur will poison the particulate filters added to the exhaust system. The same filters could theoretically be added to the older cars and then they'd require the new fuel, too. It's nothing to do, that is, with engine design, but rather with exhaust aftertreatment components.

Just as an FYI, the newer cars also require different motor oil for the same reason, i.e. protection of the particulate filter. This oil is fine for the older cars and is very likely what you'll get at a dealer in any event. A sticker under the hood, incidentally, cautions against even adding oil between changes using the wrong stuff.


I too have read that ULSD is supposed to be supplemented with additives to make it more 'lubricating'. It's not easy to find out who's correct on this. Most everything I read says there should be no problem. Then I saw George's article, but I think he's talking more about the older pre-CDI models, and I would guess just as a preventive measure. There's no telling if the lubricity additives go into every batch of ULSD. In fact, there's no assurance the ULSD is actually uncontaminated with higher sulfur grades of diesel. If anyone's at risk here, I'd say its Bluetec owners whose catalytic converter systems won't tolerate the higher sulfur content, whether or not it was inadvertantly or carelessly included in the ULSD fuel. I suppose all things considered, you may be better off with the pre-Bluetec CDI's. If my catalytic converter systems suddenly shut down and then was told by my tech at Mercedes that something other than ULSD had been used in the car, I would imagine that would void my warranty, regardless of the fact I used diesel fuel labeled ULSD at the pump. Not good. BTW, its a misnomer for MB to have dubbed the '07 and '08's "Bluetec". It's a crock that the name "Bluetec" refers to "blue skies". Bluetec refers primarily to the additive Adblue which is moot as far as the '07's and '08's are concerned. They should have spent a little more time, money, and engineering grey matter in the development of their deNOx catalytic converter to come up to Bin 5 standards without the need for Adblue.

[lkchris]

If I had a Bluetec, first thing I'd do is remove that badge and substitute CDI.

Next thing you know Mercedes may have badges that read "double-overhead-cam V6" or some such junk like a Camry.

[daddy long legs]

You know they're good with the jargon but not much substance there.

[greasy kid]

My 2005 CDI now has 21,000 mi. on it . Re; milage. Really hammered it on a 700 mi. freeway trip. 70-80 all the time. Got 35mpg. Recently set it on cruise for 30 mi. of average rolling freeway at 60 mph. Got 39mpg. It was a warm day with the a/c and sound system on.

re. Bluetec milage sticker. Have read that ULSF has 3% less energy in it so that would equate to 1 mpg less on the sticker vs the CDI.

Because I plan to keep the CDI indefinitely I am changing the oil every 6,500 mi rather than 13,000 mi. Using only the Mobile 1 at dealer. New type recommended has an m on the label and from what I understand is only available from MB. Cheap insurance. Comments?

[davewrit]

Just as a little aside - I have the 2007 Jeep Grand Cherokee with the M-B 3.0LCDI diesel engine. I have ~17,000 miles on it since May 2007.

I am consistently getting ~21-22MPG at highway (75mph) speeds. This is actual based on fills, not the trip computer which will tell me 18-20MPG. Great engine.

I decided on the Jeep over the ML or GL based on towing capacity (7400lbs) and being in industrial sales my need to drive something a little more "customer friendly", if you know what I mean.

[daddy long legs]

Because I plan to keep the CDI indefinitely I am changing the oil every 6,500 mi rather than 13,000 mi. Using only the Mobile 1 at dealer. New type recommended has an m on the label and from what I understand is only available from MB. Cheap insurance. Comments?

I'm not sure how accurate this is, but I've read some postings elsewhere that pure synthetic oils have certain additives which only kick in when the oil gets closer to 10k old. These additives are supposedly important for proper engine function, so some schools of thought say these newer oils shouldn't be changed more often than recommended by the factory. I hadn't heard this until recently. In any case, I plan to change oil as recommended, every 10k. Everything I've seen says there is no benefit in changing synthetic oils more often. On diesels, you can't go by how dirty it looks -- my oil looked dirty a week after I took delivery in August.

Mine has +5k now and gets 35 on the highway and 26 in town. The computer says my overall average since day one is 27.5. Any little differences are probably differences in driving habits. Jack rabbit starts reduce city mileage to around 22.