By on January 4, 2011

Automotive News [sub] reports that Audi may be going against the wishes of its parent company by introducing a Wankel rotary range-extender for the trial version of its A1 E-tron EREV, which will begin fleet testing in Germany later this year. Volkswagen reportedly wants each of its ten brands to agree on a common EV strategy in order to cut costs, but Audi is looking for a more refined concept for its range-extender in order to compete with BMW’s forthcoming Megacity lightweight city car, a consideration which caused the luxury brand to settle on a rotary range-extending engine. The German press reports that Audi’s decision has left it “at odds” with its parent company, and they describe the situation as “anarchic.” An Audi spokesman, however, tells AN [sub] that

There is no problem between VW and Audi

But a Wankel engine is hardly the kind of cost-cutting move towards commonality that VW had envisioned for its concern-wide EV effort, and bosses from the firms corporate headquarters have not yet commented on the story. And considering that the Wankel-powered Mazda RX-8 was recently yanked from the European market for its gas-guzzling ways, it’s hard to see Audi making the Wankel work. Still, we’ll wait for VW to comment and for the results of the A1 E-tron’s fleet testing (which will determine if the concept is production-ready) before we pass judgment.

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30 Comments on “Is Audi Wankeling Without Permission?...”

  • avatar

    Good for Audi.  Standing up to VW and telling them they were more advanced than them way back when the Original Beetle was still being pimped all over the world.  And they will continue to be without your stinking help, thank you very much!

  • avatar

    Oddly enough, the idea of having a wankel engine as a range extender in an EV car makes sense because the main benefit is essentially a very light and compact engine.  So you would probably get better electric range compared to an EV carrying around a relatively heavy and less compact conventional ICE.  However, you’re spot on that the fuel efficiency concerns when in range extender mode would be counter-intuitive to the whole basis of having an EV car.

    • 0 avatar

      That’s what Audi does best.  Fly in the face of conventional wisdom and eventually prove they were right.

    • 0 avatar

      GM was saying that it was thinking about a Wankel for its next gen Volt.  Seems like this might be the way to go.

    • 0 avatar

      While I wouldn’t want to start hypermiling a straight Wankel (does that sound dirty?), if you run it in a relatively low-torque and at the optimal revolutions, (easy to do if you’re using it as an electric generator) you can get some decent MPG numbers.  Factor in the high power-to-rate ratio and the idea of putting this into a range extending platform starts to make a lot of sense.  You can’t just drop it in where an ICE used to be, but if anyone can do the engineering right, Audi could make it happen.

      The biggest issue with the RX-8 was that to get some reasonable torque, you’re running between 4 and 6 thousand RPM (it redlines ~8600).  Of course, that’s also why it’s so much fun!

    • 0 avatar

      How much would this cost?  I think EVs can get a lot of boost from just a little bit of combustion.  Especially heat.

  • avatar

    I wonder what the fuel efficiency sacrifice is vs the weight savings? Perhaps Audi has found that it is a net positive for the car as a complete system of mechanicals, packaging and range.

  • avatar

    The significant weight reduction with a Wankel engine should increase the EV-mode efficiency and range, so that’s a step in the right direction.  In an EV you’re not supposed to use the range-extending engine very often, so who cares?  Also the Wankel engine is smaller and has less parts.
    Also, I suppose that the gas consumption could be reduced significantly by using a much smaller and much less powerful engine than in the RX8.

  • avatar

    Good to see Audi innovate, but if I were VW I’d be angry that Audi weren’t looking a turbines when their Uk competitor Jaguar evidently is….

  • avatar
    Dr. Kenneth Noisewater

    Why not a microturbine?  You could probably fit it to a class 2 or 3 hitch without a trailer, including maybe 5gal of fuel..

  • avatar

    “And considering that the Wankel-powered Mazda RX-8 was recently yanked from the European market for its gas-guzzling ways, it’s hard to see Audi making the Wankel work”:
    So you think all those engineering nerds in Ingolstadt heven’t thought of that?
    The fuel efficiency problems of the Wankel are no big engineering problem, given the Audi solution uses an engine running at constant RPM. You can easily optimize any engine for low fuel consumption in a very narrow powerband.
    In addition, the smaller the engine size, the bigger the relative weight penalty of a piston engine compared to a Wankel.

  • avatar

    It will be interesting to see if Audi can make a better Wankel than Mazda. Fuel mileage, emissions and oil consumption were challenges for the RX-7/8. A college roommate in Boston bought one of the first RX-2s back in the early 1970’s — a revolutionary car for its day.

    • 0 avatar

      I doubt it. Mazda has years’ experience with Wankels that Audi lacks. There is no way to make a Wankel efficient–too many design constraints that force inefficiency. (For one thing, the most most efficient combustion chamber would be spherical, which is why the hemi is so good, but the Wankel is stuck with more of an elongated pancake shape–about as far from spherical as you can get.)
      Using a Wankel as a range extender suggests to me that Audi is assuming buyers would rarely need to use the range-extender, as if that’s the case, the reduced electricity use because of the reduced weight wouild be greater than the excess petrol from having such an inefficient engine. I suspect Audi must have made some calculations as to where the tradeoff point lies.

  • avatar

    Bad boy Audi wankeling locked up in the bathroom?
    As Autocar in their review say, Audi managed to get a 245cc, 20bhp engine along with the li-ion batteries under the boot floor without compromising the luggage space at all. All that in a sub 4 metre subcompact.
    The only problem is that 20bhp is certainly not enough for motorway cruising plus recharging the batteries so I guess Audi would have to beef up the engine a bit before any real world application.


    • 0 avatar

      Audi is an adult he should be able to wankel anytime he wants. They are going to do it anyway, they will just wait until you are not around. Remember, there are two types of people, people who wankel, and liars. ok, i’m done.

  • avatar
    Beta Blocker

    If it weren’t for the wankel’s problems with fuel economy, along with its lack of torque, there would be a Mazda RX-8 sitting in my driveway, as opposed to a Mazda 6.

    No doubt someone in senior VW management is well aware of the lack of sufficient fuel economy with the Mazda RX-8’s wankel engine, and its perceived reliability issues — to the extent that what could have been a very popular sports car in its niche is consigned to failure in the marketplace.

    • 0 avatar

      See my comment several above. And if it weren’t for the Wankel’s fuel economy problems, I’d also have an RX-8. I had the use of one for a week when I was writing about the question of whether the fuel economy could be improved (in brief, NO!), and I loved the car, and I loved the fact that a sports car had a useable back seat, and four doors. The torque was plenty for me.

  • avatar

    As an old engine development guy, I’ve been thinking about mini-rotaries in this role for some years now.

    Considering the traditional Wankel problems:
    – lack of torque
    – excessive thirst
    – high emissions
    – durability of the tip seals on that famous trichoidal rotor

    it could very well be that each of these will fall on the side of goodness as the motor is moved from a prime-mover role, with the related acceleration and deceleration, and designed to act in a gen-set role, where the rotary would hum along at a more-or less constant speed this being optimized for durability, economy and clenliness.

    It could be, that this is the application that Wankel’s namesake technology was born for.

    • 0 avatar

      I agree totally – if you remove all of the compromises that a rotary needs to be a viable powerplant as a “prime mover”, you’re left with many advantages that could outweigh (cough) its inherent weaknesses. For one, you could optimize the shape of the combustion chamber and get rid of the extra spark plugs required for variable RPM operation.

  • avatar

    And, for a luxury car the wankel offers near turbine like smoothness.

  • avatar

    you can’t compare that to Mazda. In this case the Wankel would drive a generator with constant speed and high rpm for relatively short periods of time. This is much better for the Wankel (and turbines as well) than changing rpm, changing loads etc. as you have with typical IC cars.
    About weight savings, this probably is not so much since the fuel, cooling system etc. still is the same. Considering they could drive it in some type of hybrid mode it only needed some 40 hp.
    Constantly charging the battery, and when acceleration is needed, the E-motor helps.

  • avatar

    diesel wankel? :D

    • 0 avatar

      I was pondering this too, but my guess is that the rotor tip seals (and other components) would have a hard time with the high pressue loads needed in and generated by the Diesel cycle. No time today for a long literature search, but eh following article on Wiki claims that a german firm owned by a former colleague of Felix Wankel had solved both the tip seal issue (integrated tip seals) and NOx problem, but the company went bankrupt in 2000 before really being able to develop/sell the idea further.

      Mazda did, however, IIRC achieve road-going certification from the Japanese authorities for a hydrogen-fuelled rotary test car.

  • avatar
    Uncle Mellow

    Haven’t Mazda made some hybrid cars with a hydrogen powered wankel range-extender ? As already stated , lack of torque and other wanbkel drawbacks don’t apply when it is being used to charge batteries only.

  • avatar

    Basic creative thinking is an improvement for any part of VW-Group who have been doing the automotive equivalent of hands over ears “la-la-la-la-la-diesel-la-la-la-la”.

  • avatar

    Don’t forget the bones of NSU are in Audi somewhere. It would be funny if the offspring of Wankel was in the basement somewhere, hidden away amongst the detritus of Horst, Wanderer and Autounion beavering away at new uses of old tech.

  • avatar

    I think its an interesting choice for a hybrid because of the rotary’s not-yet-mentioned achilles heel: flooding. Many a rotary owner has experienced difficulty starting their car after turning it on, moving in 10 feet, and turning it off again. The engines don’t like this. Im not sure how often it would cycle on and off in a range extended EV application, but it could be an issue.

  • avatar

    Mmm … Did the Audi people really look the “etron” word in a french dictionary ?

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