Mileage Loop: Mercedes Benz Bluetec SUV

When Mercedes Benz first introduced Bluetec clean diesel technology in the 2007 E320 Bluetec sedan, many saw the comeback of diesel in the United States. The idea of a luxury car that gets better than 40 miles to the gallon—with particulate filters and after-treatment devices to minimize diesel emissions—sounded like a winner. But in the end, those emissions were only clean enough for 43 states.

Since then, Benz engineers incorporated a liquid called AdBlue into the exhaust system that further scrubs NOx particles. The new and improved Bluetec system is now 50-state legal and will be featured this fall in a trio of high-end Mercedes SUVs: the R, ML, and GL. We had an opportunity to drive one of these SUVs, the Mercedes R320 Bluetec, to evaluate its efficiency. The results fell short of our expectations.

Our first driving loop was a highway route that took us westbound from Baltimore to Cumberland, Maryland—a 142-mile stretch on Interstate 70. The road posts a 65 miles per hour speed limit, though most traffic was moving about 80 miles per hour. This test route yielded just 18.5 miles per gallon. The EPA rates the vehicle at 15 in the city and 23 on the highway, so we were expecting something, at least, in the low 20s. Heading back to Baltimore on the same route confirmed our findings with a calculation of 19.2 miles per gallon. More disappointment.

Our second test loop consisted of urban-suburban driving in and around the Washington, DC metropolitan area. The highest speed traveled was 40 miles per hour, and there was considerable stop-and-go traffic. Once again, the Bluetec SUV fell short. Where its sedan counterpart two years ago managed stellar numbers in city driving, the Mercedes R320 yielded just 14.4 miles per gallon on a 110-mile test drive.

Mercedes introduced its Bluetec vehicles to most of the country two years ago, and is now prepared to debut the cleaner diesel offerings on a national stage. But even before the curtain rises, there may be trouble backstage. The current price of diesel is about 20 percent higher than gasoline. That will keep some customers away. In addition, Mercedes is applying the diesel technology to luxury SUVs, in a time when the economy is struggling and larger vehicles have fallen out of favor. With the disappointing fuel economy numbers we experienced, the argument for diesel in America may be further weakened upon release of Benz’s newest Bluetec SUVs.

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  • Achilles

    Forget Diesel Hybrids….

    The fuel consumption figures for the latest versions of the BMW 330i and 335d appear deep in the International press release for the new BMW 3 Series. The 330i is about to get a direct injection gasoline engine. If both cars have an automatic transmission, the 335d is only 0.1 seconds quicker than the enhanced 330i to 62 mph, and is only 7% more economical. But, with diesel fuel now costing as much as 20% more than gasoline, the 335d is going to be more expensive to run. Who will want to pay extra for the less refined and ‘dirtier’ diesel if there are no real savings in fuel costs? And the 330i produces slightly less (~3%) CO2 than the 335d, which should finally convince everyone that diesel fuel will, and should, never become popular in US cars.

    Consequently, it’s hardly surprising that the proportion of diesel cars sold in Germany is predicted to decline, given that the price of diesel fuel at the pumps is now roughly the same or more than gasoline in Germany, where it was taxed less until recently. In the UK, diesel fuel now costs an average of 12% more than petrol. Watch the ‘pub experts’ gradually accept that diesel is no longer the smart choice, once they understand that a new direct injection 330i costs less per mile to fuel than a 335d. In France, the ‘playing field’ is still tilted in favor of diesel by the French government, but all the governments of the EU have committed to move to tax parity, so the ‘retreat from diesel’ could soon turn into a rout.

    For the full picture, see:

    Whether the next 3.0 liter 3 Series is labelled 330i or 328i in the US doesn’t really matter, and BMW isn’t saying yet. What does matter is that a cleaner, more economical and more powerful replacement for the current 328i is on its way, which effectively makes the latest version of the 335d redundant in all markets which don’t ‘under-tax’ diesel fuel. And check out the 320i. BMW has not allowed the previous version to be shipped to the US, despite its impressive fuel economy. BMW might now want to reconsider, given the renewed interest in fuel costs. Certainly, there will be a host of US customers for it, as the 2.0 liter versions’ dominant share of 3 Series sales in Europe demonstrates.

    Now imagine a hybrid BMW 320i. So you can forget diesel hybrid cars in the US. Why would a manufacturer bother?

  • jmbrendel

    If you want good fuel economy in an SUV, just buy a hybrid Ford Escape: 34 mpg local / 30 mpg highway for the Front-wheel drive version. Available now, and made in the USA (Kansas City, Missouri).

    It would be nice if Ford offered the hybrid Escape in a flex-fuel version that can run on diesel, biodiesel, and/or E85. Not sure if they offer that yet.

  • Boom Boom

    Hopefully those numbers are an anomaly and most of the production vehicles get better than that, but probably not……. If the diesels the Europeans are sending over are going to get only a small bump over gas versions, they’re going to fall flat. I’d be interested to see a real world test of the new Jetta TDI. (The old TDIs got impressive economy.)

    P.S. an Escape Hybrid that ran on diesel, bio-diesel AND E85 would be quite a feat of engineering. (The current Escape does pretty well on regular gas.)

  • PatrickPunch

    Fuel economy is a combination of:

    – Right size of vehicle
    – Correct powertrain for the application
    – Good driving style

    Then you can get 35 mpg or better in a non-hybrid and 50 mpg or better in a hybrid.

  • Collin Burnell

    Hey JB.

    Ford does have an E85 Hybrid Escape that they sell to fleets. I just saw one the other day here in Las Vegas with Southwest Gas logos on it.

  • Old Man Crowder

    “The results fell short of our expectations.” You don’t say!

    Can anyone name a vehicle that gets better than expected fuel economy in real-world driving? But getting 19-ish mpg when you’re expecting 43 is horribly pathetic.

    Mind you, it’s not entirely clear to me whether the author was doing 80, keeping up with traffic, or maintained the posted speed limit. Fuel economy plummets the faster you go.

  • walz

    Once again another luxury car company shows its more about status and appearance then actual value and sound engineering.

    18.5 mpg not good enough

    If this vehicle averaged 38.5 mpg then I would say great engineering Mercedes but its like other bland products from BMW. Performance yes, zip yes, but lacking good sound engineering for the price.

    Like the other person said get a Ford Escape Hybrid better tech better value, (That is if you can actually find one)

  • Bryce

    A big seller….I am sure… Better luck next time Mercedez!

  • steved28

    Crowder, they weren’t expecting 43, they were expecting 23.

  • Anonymous

    Wow! Thanks for the heads-up, please examine other diesels as they come to market, and keep us informed about the direct-injection gas engines. The next few years could be exciting ones for those who want more efficient cars and it’s great to have this website. Thanks again.
    BTW we also are happy with our Escape hybrid SUV — fuel costs have been below what we expected, the car has been rock-solid reliable, and the hybrid also needs less maintenance than the gas version. Plus — it is far more fun to drive than the Explorer it replaced!

  • Anonymous

    Why are the small diesels not available here that Mercedes sells in Europe? About three months ago I was in Belgium and rented a Mercedes that looked a lot like a VW Golf. It had a very nice roomy cabin, plenty of power from a turbo diesel, and got about 45 miles per gallon as near as I could calculate it; kilometers per liter vs miles per gallon. Diesel is about 25% cheaper in Europe than gas, by the way.

  • bplus

    “Diesel is about 25% cheaper in Europe than gas, by the way.” Maybe you mean the other way around :). Diesel is the most expensive fuel in Europe (the world too I guess).

  • Michael-59

    Patric is making a perfectly valid point. I bought a used Suzuki SX4 with a 2.0 L engine, AWD, and 5 speed manual. It’s a nice peppy engine in a car with all the features I wanted and it is fun to drive because the power to weight ratio is good.

    The trip computer in this car had not been reset by the former owner and indicated they were averaging 23 MPG over the course of 8000 miles. I have put 4000 interstate miles on the exact same car and my average is 33.4 MPG. For a couple of weeks it was driven entirely in town in stop and go traffic and averaged 28.9 MPG.

    Mileage is determined to a huge extent by your driving habits. I accelerate carefully, try to maintain a steady speed of 30 or 35 MPH in town and 60 to 65 MPH on the interstate. I watch traffic lights and try to slow down early to avoid completely stopping at red lights, then accelerate slowly with the green. People continuously blow by me every day during my 1 1/2 hour commute. The same ones who are bitching about the price of fuel. If they drove like me they would take about 5 minutes longer make the 50 mile trip to work and save about 25% on the cost of fuel. This is an absolute fact. Been there, done it.

  • Anonymous

    No, bplus, three months ago gas in Belgium was 2.26 Euro per liter and diesel was 1.72 Euro per liter. I know thats a lot more for both than what we pay here in the USA, but that’s always been the case. The fact remains that deisel was a lot cheaper than gas. That’s why so many more folks over there drive diesels. I did notice someone else posted a comment about European governments were now trying to balance the taxes on fuels to try to gain equity. That may be the case now, I can only report what I paid 3 months ago.

    As a side note it might be worth mentioning that people in Europe have to pay a substantial tax on their car every year based on the size of their engine. That’s one reason they have decent driving cars with 1.5 to 1.8 L turbo charged engines. A person would have to pay as much in taxes as car payments if their engines were sized like most of ours.

  • bplus

    Yes I was wrong, there are indeed countries in Europe where diesel is cheaper. I didn’t now that even though I live in Europe. You are also right with the taxes based on the engine size. On my VW 1.4 TSI I pay the lowest tax possible (for a <1600 cc engine you pay about 3 dollars per 200 cc, while for an engine >3000 cc you pay 50 dollars per 200 cc, so there is a difference).

  • Dom

    I’d be interested in reading what that same SUV with an equivalent (read=similar torque ratings) gasoline engine gets driven that same route. I have a sneaking suspicion it would shed a more positive light on the diesel model…

  • Old Man Crowder

    Steved: You’re right, although I was more referring to this line…

    “The idea of a luxury car that gets better than 40 miles to the gallon—with particulate filters and after-treatment devices to minimize diesel emissions—sounded like a winner”

    I stand by my statement of “horribly pathetic”.

  • Dom

    Old Man Crowder – this isn’t a luxury car, it’s a luxury SUV. There is no SUV that I’m aware of that gets 40mpg, diesel, hybrid, or otherwise. That sentence is just silly. If you want to see a diesel car that gets >40mpg check out a Jetta TDI or something similar, not a luxury car. Anyone that can afford a R320 can afford mediocre fuel economy. The point that I think should be made about this SUV isn’t that it’s some sort of hybrid killer, and it doesn’t get outstanding fuel economy. But it does get better fuel economy than the gasoline model, and it probably has gobs more torque as well. The Lexus luxury hybrids rather mediocre fuel economy as well, which is what this Mercedes should probably be compared to.

  • manti

    Volkswagen TSI engine wins its category again for Engine of the Year
    Best gasoline engine on the market atm.
    see link:

  • Forrest Dungan

    I agree with everyone that talked about driving habits. I live in Raleigh, NC and drive to Wilmington, NC several times a year. Taking the 140 mile trip at the posted speed limit of 70 saves about 10-15 dollars per trip. I used to drive about 90 and wonder why I had to fill up my 12 gallon tank as soon as I arrived.

    Watch your rpms, and don’t accelerate like you are on a drag strip and it is amazing that you’ll go a couple more days on the same tank of gas.

  • harvid

    I’m not sure how you’re driving the vehicle, but I would question how you’re driving the vehicle. I actually own a 2009 R320 Bluetec which is now two weeks old. The day I picked it up, I drove straight off to Rochester NY for US Thanksgiving from our home in Canada (a four hour drive). Our speed was a constant 120 km/h, save for 10 minutes of idling at the border and a brief stop for coffee. Somehow, I managed 28.3 mpg on the trip according to the trip computer. As with any engine, aggressiveness of driving style will impact economy.

  • Travis1985

    I kinda think that test was biast B.S. myself. And I do not think hybrid technology is the wave of the future. Repeated tests by automobile journalists show that the new clean diesels can consistently get better real world economy than a hybrid. Even Honda is planning to offer a clean diesel to take out the hybrid market lead by Toyota. With the new clean low sulfur diesel available in the US since 2006 and the new clean diesel technology diesel will soon be directly competing with the hybrid market. In fact, VW’s bluemotion polo a clean diesel available in Europe, beat the prius for least amount of emissions produced, on top of this it got much better fuel economy. As we are running out of fossil fuels, diesels are a viable solution as they are generally thirty percent more efficient than gasoline engines and use less fuel to go farther. Hopefully with clean diesel, we can use less fossil fuels, and release less emissions than gasoline cars.

    It think the hybrid owners need to wake up and realize that their are effective alternatives on the horizon and quite stereotyping diesel as a dirty fuel. And as for gasoline direct injection, it is extremely viable but not available yet and I would say definitely the next best technology to look out for. And E85 flexifuel? any car can run on that with simple mods, hell all of brazil runs on flexifuel, the problem is flexifuel is not offered at many gas stations in the states so whats the point? It’s called greenwashing people, all the american car companies advertise that their cars can run on E85, and people think they are clean but the clean fuel is unavailable. And speak of greenwashing the chevy malibu hybrid? what a fucking joke, apparently it is barely an improvement over the original. Don’t discount other technologies, hybrid’s are not necessarily the be all and end all.

  • maggiedon

    I believe that Mercedes is actually looking to the future with the new cars, the financial crisis won’t last forever and people will have increased interest on SUVs again, why not meet their expectations with a hybrid? Mercedes is not all about luxury, you can actually find Mercedes Benz Parts on reasonable prices, after all each car brand is addressed to it’s own market niche.