• Mar 17, 2011
2012 Mercedes-Benz SLK – Click above for high-res image gallery

The newest gasoline engines from Mercedes-Benz feature cutting-edge lean-burn technology that leads to fewer harmful emissions and a 10 percent improvement in fuel economy. Well, the new engine tech, which requires a much leaner fuel-to-air ratio, is making its way into many mills, but apparently not the ones destined for these United States.

Ward's Automotive quotes Daimler powertrain development vice president Bernhard Heil as saying that the gasoline in the U.S. contains sulfur at the rate of 95 parts-per-million; about twice as much as can be tolerated by the new engines. The problem? Excess sulfur apparently clogs the nitrogen oxide-capturing traps.

So, is the U.S. the only country lagging behind Europe in removing sulfur from its gasoline supply? Far from it. Heil points out that the gasoline in Africa and many areas of Asia also contain too much sulfur for the lean engines. The first engine to feature the technology is the direct-injected 3.5-liter V6 destined for the C350 sport sedan and the SLK roadster seen above. The 302-horsepower mill will not (obviously) utilize lean-burn tech here in the U.S.

[Source: Ward's Automotive]


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  • 50 Comments
      • 3 Years Ago
      MB should ask Hyundai how they manage to reliably produce over 400hp all on regular fuel.
        • 3 Years Ago
        what does your question have to do with this matter? This isn't about MB's power output. It's about their Lean Burn technology which cleans up emissions and uses less fuel.
        • 3 Years Ago
        "The new Hyundai 5.0 takes premium."

        no but my point was it can run "safely" on regular.


        Specifications[5] for Equus' 5.0L Tau V8 engine:

        * Horsepower: 429 hp (320 kW)
        * Torque: 376 ft·lbf (510 N·m)
        * Displacement: 5,038 cc
        * Compression ratio: 11.5:1
        * Block material: High pressure die casting aluminum block
        * Cylinder head material: Aluminum
        * Valvetrain: Dual Over Head Cam (DOHC)
        * Valve timing: Dual-Continuous variable valve timing(D-CVVT)
        * Variable induction system
        * Fuel delivery: Gasoline Direct Injection / Electronic Fuel Injection

        * Recommended fuel: Premium Unleaded, though it can run SAFELY on regular gasoline with reduced performance

        • 3 Years Ago
        The new Hyundai 5.0 takes premium.
        Hyundai uses 'sidedraft' direct injection, where MB uses 'downdraft' direct injection mounted directly adjacent to the spark plug.

        This is a matter of not being able to uses lean/super-lean combustion because of the sulfur content damaging the zeolite.
      • 3 Years Ago
      Is this the actual reason why GM didn't ship the full fat Insignia VXR into their Buick line-up? Just because the fuel in US is too dirty for their Euro engines?
        • 3 Years Ago
        No, it's because that engine is old tech and GM wants to retire it. They just pulled it from the Cadillac SRX too, about a year after introing it.

        I wouldn't expect to see GM announce any turbo V6s in the US until they have a DI one to offer.

        The idea that GM couldn't offer the low tech Saab turbo V6 when they offer the DI 2.0T LNF EcoTec is bizarre.

        Also Saab still ships that turbo V6 in the US (9-5 sedan).
      • 3 Years Ago
      Yes, sweet crude is low sulfur. For diesel fuel, we went from 500ppm (parts per million) sulfur down to 15ppm in September 2007. The method used to extract sulfur is to inject steam into the diesel fuel. The water attaches to the sulfur and is removed. From what I have read, the cost to reduce sulfur down to 15ppm added another 5 to 8 cents to each gallon of diesel fuel. I would expect similar costs associated with reducing sulfur levels in our gasoline. In other words, greater efficiency comes with a higher price tag.
      • 3 Years Ago
      isn't the sulfur problem the same thing that led to so many ruined BMW engines a few years ago? I remember something about their Nikasil linings being corroded by the sulfur in our engines which BMW did not take into account.
      • 3 Years Ago
      Two things:

      Why does MB build engines that can't handle something like 80% of the worlds population? Are they just that naive to build something and be careless enough to assume that the rest of the world has different gas? They should have designed it under the assumption o higher sulfer ratings. I don't build a beach how in Venice and try to sell it in Wisconsin? That's just dumb.

      2nd Thing - All this complaining on US gas - do you realize we still pay absurdly less than Europe?
        • 3 Years Ago
        People shouldn't always design to the least common denominator. Maybe they're building engines that require better gas because they'll need that in order to meet emissions regulations in those countries. Or maybe they don't want to be held back by people falling behind. Can you imagine if smartphones were designed so they could be 100% utilized by the majority of the population? We'd be back in the brick phone days!

        I can't imagine living in a world where everything is designed for the least common denominator.
        • 3 Years Ago
        Isn't it the engineer's job to always look ahead and design for tomorrow? If we just kept our sights on what's available right now, in the here and now, we'd never progress at all. Sulphur should probably be taken out of all fuels, and it will eventually for the very reasons MB's lean burn engines demonstrate: lower emissions and better fuel economy. Through the past several decades, MB has consistently pushed the envelope with tech that eventually makes its way down the automotive food chain to every one. I'm afraid that with their management team they have today, that might not always be the case. In many ways they seem to more interested in being all things to all people rather than the "leader of the pack."
      • 3 Years Ago
      obviously not

      vs

      not obviously
      • 3 Years Ago
      Sigh.
      • 3 Years Ago
      Nobody has mentioned that the grade of oil that is refined in the USA is simply different. WTI (West Texas Intermediate) simply contains a higher content of sulfur from the ground. Brent Crude, which most of Europe uses has less sulfur.

      The second factor is refinery technology. We need newer better refineries.
        • 3 Years Ago
        I agree, especially when our current refineries were around when we were still using leaded gasoline.
      • 3 Years Ago
      In other news: The newest gasoline engines from Mercedes-Benz are too sissy to handle superior US fuel.
        • 3 Years Ago
        There is nothing superior about having sulfur in gasoline.
        • 3 Years Ago
        That sounds like it could be a direct quote from Bill O'Reilly...
      • 3 Years Ago
      Fuel standards? I'm inclined to believe the fuel refiners' PR people would call this 'burdensome regulation' that would 'destroy the industry.'
      They said the same thing about taking lead out of gasoline, but they're still running a profitable business sector.

      There is a similar issue with regard to using U.S. diesel in the most advanced fuel systems from VW/Audi. Amongst the vehicles NOT accidentally mis-fueled, insufficient fuel lubricity is causing a statistically-significant number of high pressure fuel pumps to self-destruct. The Feds are finally investigating.
      • 3 Years Ago
      As a long time tech for the pointed star brand in the US, I had to chime in here. We've had drivability issues with engines not idling smoothly and "not quite misses" under throttle for years based on the poor quality of US fuel. At least in Chicago, the cars seem to run best on Shell 89 octane (I know, weird). This is not something new and Mercedes ( and other German car manufacturers) have been dealing with this for many years. I came into the business in the late 80's and this was common knowledge amongst the older techs then. It's unfortunate, but at least they've finally come out and said their engines will not function properly on the poor quality fuel we have here.
      • 3 Years Ago
      the MB isn't the first car that requires cleaner fuel. IIRC the V8 Audi S4 was the first.
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