• Jul 25, 2007

Diesel technology has improved by leaps and bounds, but the trouble is, it still runs on diesel. In the American market, at least, finding a diesel pump is still a pain compared to filling up with conventional gasoline. Mercedes-Benz says it's found the solution with a new developmental powertrain concept it calls DiesOtto.

We first reported on the project a couple of years ago, but the German automaker now has a functioning prototype. Rather than actually running on diesel, the DiesOtto engine is said to incorporate the benefits of a diesel engine, but runs on regular old unleaded. The prototype is a 1.8-liter four-cylinder engine that uses direct injection, variable compression, turbocharging and something MB calls "controlled auto ignition" to deliver 238 horsepower and 295 lb-ft of torque, with a claimed return of "less than 6 liters per 100 kilometers", which translates to 39.2 mpg. Those numbers, Benz claims, are not based on a small car (like the C-Class or smaller) but on a large sedan (like the S-Class). They may not be entirely revolutionary figures, but any way you look at it, they're damn impressive.

Mercedes hasn't put a timeline on producing and marketing a powertrain based on the DiesOtto prototype, but says it's a "feasible proposition in the midterm". We certainly hope so.

[Source: Edmunds' Inside Line]



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  • 50 Comments
      • 7 Years Ago
      I've been driving Diesel cars since 1982, and really have never, ever, EVER had any issues finding fuel.

      One of the fantastic benefits of having a Diesel engine is the ability to fuel it with virtually ANY combustible oil. In a pinch you can pour anything from canola oil to used motor oil into a Diesel and it will run. If you can't find a pump, you sure as hell can find a grocery store! Buy some Crisco and keep driving.

      So there's something this fancy Benz engine can't do.

      Gasoline enjoys ubiquity today, but that wasn't always the case, and someday won't be again. Back in the days of the mini-oil crunch of the 80s, when gasoline first topped a dollar a gallon, finding gasoline was sometimes tough in rural areas. Stations would run out. Not so Diesel... it was always available and back then it was half the price of gasoline. So just because things are one way now, don't assume they'll always be that way.

      --chuck

      • 7 Years Ago
      @ Ian -

      the geometry of a Wankel engine means that near the time of combustion, the compressed charge occupies a suboptimal elongated space. That's why such engines often feature two spark plugs per rotor. HCCI combustion might improve on spark ignition at low engine speeds, but at some point it becomes impossible to control reliably and you get misfires. Since Wankels don't deliver much torque at low RPM, there would be no need to manage a transition to SI based on torque.

      The biggest issue - other than the fact that only Mazda really knows anything about producing Wankels these days - would precise control of retained EGR, given that there are normally no valves.
      • 7 Years Ago
      Most Americans can't stand the smell of diesel fuel. This engine solves the problem.
      • 7 Years Ago
      Diesel... As in diesel thermodynamic cycle?
        • 7 Years Ago
        ""controlled auto ignition""

        It would appear perfect timing with compression ignition. Electronics?
      • 7 Years Ago
      Are you kidding me? I can't even remember the last time I've seen a gas station here in California that DOESN'T offer diesel.
      • 7 Years Ago
      I don't know where you are when you can't find a diesel pump. In the south east and the mid west they are everywhere.
      • 7 Years Ago
      Man, it seems that people can't read and are jumping to conclusions...

      There haven't been any real specifics about the engine and already it's being blasted with "it's a diesel" (it's not), "it has long turbo lag" (how do you know?), "people will use the wrong fuel" (how many times have you bought a new car and put diesel in it by default?), blah blah blah...geeze, it's almost like car people are ANTI technology
      • 7 Years Ago
      On my 15 mile commute to work there are seven of the ten gas stations have diesel.
      • 7 Years Ago
      "...I don't recall seeing many diesel powered vehicles sitting on the shoulder out of fuel."

      That has nothing to do with the type of fuel the vehicle uses. :-)
      • 7 Years Ago
      WOW, sounds like the best of both worlds!

      http://www.benzForum.com
      • 7 Years Ago
      Surely a wankel type rotary engine (like in the Mazda RX7/8) wouldmake this ideal basis for this type of ignition and fuel delivery system?
      • 7 Years Ago
      Someone correct me if I'm wrong, but don't a lot of oxides of nitrogen get formed at really high temperatures in gasoline cars? I would think that compression ignition requires high temps by default, so MB will have to come up with some new catalytic converter to get this to pass emissions regulations. If I'm wrong, please let me know.
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