By on May 9, 2013


God bless the blogosphere. All it takes is one throwaway remark for something to become a widely reported rumor heard ’round the world.

Autocar, a UK magazine that is fond of publishing sketches, conjecture and other wild-ass rumors in the best tradition of Fleet Street, published another piece on the upcoming Mazda MX-5 that included this paragraph

A diesel option is being considered, but the lightweight and high-revving capabilities of a petrol engine are more desirable to Mazda. There are also concerns over the market viability of a small diesel roadster, which might prove difficult to sell.

And that should be it, right? Autocar themselves basically debunked this ridiculous notion. Nope! Not wanting to be left behind in the race to the bottom to “get it first” the blogs picked it up en masse and reported it as fact. A Google search for “MX-5 Diesel” returns 2,200 results, which is 2,200 too many.

It should be obvious that this rumor is absolute bovine manure. A diesel engine is heavier than a gasoline engines, does not rev as freely and has a completely different character. It is everything that Mazda does not want in a lightweight sports car. Aside from the characteristics of the engine itself, the car would have to be engineered to carry a much heavier engine from the get-go, something that would have a negative impact on weight and handling targets.

A diesel may have been briefly considered at some point in the development process, but believe me, it is not happening. If it does, we won’t see it in North America. We’re more likely to see an army of automotive bloggers who aren’t ruled by the all-mighty click before we see an oil-burning MX-5.

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29 Comments on “Anatomy Of A Rumor: There Won’t Be A Diesel MX-5...”

  • avatar

    There’s probably two people on the planet who want a diesel MX-5. I just can’t imagine the demand for such a car. The idea seems absolutely ridiculous to me.

    • 0 avatar

      I agree. Diesel sports cars haven’t caught on for fair reason.

    • 0 avatar

      As far as 2,200 too many hits, I would guess closer to 2,199. There’s always someone out there who sees an unbearably light body and wants to shove a diesel in it. My take is that (does what it says on the tin) is glad they still have time to be the only ones with a diesel miata.

      Note that somewhere on that site is a link to a diesel corvette (note, the diesel was a big block [sized] V-8, not quite the same as this rumor).

    • 0 avatar

      The car must think so too… It appears to be laughing at the idea.

  • avatar

    There has already been a diesel Mercedes SLK, Audi TT and when it was still on sale ALFA Spider.

  • avatar

    So what? Some day, someone will swap a SkyActive turbo diesel into an NC. And it will be smoky and wild and cool, like a piece of homemade Alligator jerky washed down with a Sapporo.

  • avatar
    bumpy ii

    Well, the Sky-D has pretty much the same block and internals as the gas version, so it’s as close to sporty as any diesel is gonna get. I’m sure someone will do the swap before the ND goes out of production.

  • avatar

    “A diesel engine is heavy, low-revving and worst of all, a diesel. It is everything that Mazda does not want in a lightweight sports car. ”

    I mean it’s not like anyone like Audi has been successfully winning sports car races like Sebring and LeMans running diesels.

    • 0 avatar

      Come on Ronnie, a purpose-built car like the R18 and a lightweight roadster like the MX-5 have nothing in common.

    • 0 avatar
      juicy sushi

      Yes they have, although the motors are heavier, produce less power than the competition (for a given displacement) and are only competitive when given massive displacement and boost-level breaks.

      A good discussion of the ACO’s rules and their effects on the comeptitiveness of diesel entries at Le Mans can be gained from Mulsanne Mike’s website.

      • 0 avatar

        Definitely the definition of an unfair advantage. Extra displacement, variable geometry turbocharging, larger air restrictors.

        That being said… I would love to see a diesel MX-5. Just because.

    • 0 avatar

      Unless all parties are unrestricted in what they can do to win, I don’t really put much stock in how a vehicle places in a racing series where there are multiple technologies competing.

      I don’t care if a diesel Miata would be faster than a petrol Miata, I just don’t think the strong-then-fall-flat-on-its-face nature of a diesel’s power delivery would be all that enjoyable in a lightweight roadster.

  • avatar
    Jean-Pierre Sarti

    i am not sure i buy your argument.

    for the people who buy miatas for their small , cute and convertible factor and of those i dare say most almost always choose the automatic option i can see a diesel option making sense. imagine a miata getting vw tdi mileage….

    a small fuel efficient diesel option would be better than a hybrid maybe.

    anyway, not all miata buyers are scca racing potential dreamers.

    • 0 avatar

      “most almost always choose the automatic option”. Then they aren’t a large section of the miata/MX5 buyers. Even if they aren’t planning on joining the spoiled children, they appear to like to drive.

      A quick check on carmax (miata/MX5:unlimited distance)
      [cars available]
      Automatic transmission: 28 Manual: 40

      Impressive. Some comparrisons:

      Porsche (all) 66 : 40
      911 12 : 12
      boxster 10 : 17
      corvette 59 : 54
      camaro 76 : 58

      Maybe they are just dumping the manual, but I’m guessing it sells pretty well.

      • 0 avatar
        Japanese Buick

        When I bought my NC last year to replace my wrecked NA, a dismayingly large percentage of the new ones available were automatic. At higher trim levels, I’d estimate the Miata slush box percentage to be north of 70%. I had to go to a neighboring state to get a manual PRHT GT. Sad.

        Back in the NA, NB days, slush box Miatas were rare birds indeed. No longer.

  • avatar

    Silly, but BMW does makes some thunderous diesel cars…not impossible.

    Just short shift and you are fine.

  • avatar

    If we are talking about an overboosted, overfueled, black smoke spewing, way to much horsepower, 2 seater roadster then sign me up (in 5-10 years when they get cheap) otherwise there really is no point. People who buy a Miata aren’t looking for any of the benefits of a diesel, and sure don’t want any of the drawbacks

  • avatar

    I am surprised Derek was so easily drawn in by the old thinking on diesel.

    “A diesel engine is heavier than a gasoline engines, does not rev as freely and has a completely different character.”

    The current (and last) generation of the VW Jetta have had the SAME weight between the N/A motor (2.5L) and the diesel (2.0L). The Turbo 2.0L Petrol weighing in at almost 60kg HEAVIER. Darn those heavy diesels and their torque-y ways!!!

    Europe has had diesel convertibles for while now ( so why shouldn’t Mazda go that route? It is not like the current Miata has a massive power output that putting a diesel in it would be a handy cap. The current Miata (Mx-5) only has 170hp and 140lbs-ft, earlier versions barely had 140hp. Imagine an MX-5 with 200-300lbs-ft of torque but a similar weight to the current car.

    So it does not rev as high, most driving is done in the lower revs anyway… why not have the power where people are likely to USE IT? I mean people who actually buy Miatas, not internet trolls who cry blue murder at the mere thought of changing a car they have never owned, nor would, because it is a “hair dressers car”.

    • 0 avatar
      juicy sushi

      The Mazda 6 diesel is 200lbs or so heavier than the gas engined model, if I recall correctly, so I think that the weight difference of a diesel engine still is a valid concern for the Miata. And people who buy Miatas are not buying cars for torque.

      • 0 avatar

        Exactly. I am not a diesel hater by any means, but the case for a Miata diesel is rather weak.

      • 0 avatar

        You are right, they are not Torque people… but they are hardly HP people either. They are convertible or cornering/handling people.

      • 0 avatar

        Where did you get the Mazda6 comparison? The UK site has TBD listed for weight, and obviously the US spec sheet doesn’t have the diesel stats yet.

        • 0 avatar
          juicy sushi

          I remember reading it in a UK review, but haven’t been able to find it since. I did notice on Honestjohn’s website that the gross weight listed for the equivalent diesel is 100kg or so more than the equivalent gas model. (1935kg vs 2055kg for SE Hatchback models)

    • 0 avatar

      Those VW gas engines are iron block engines. Probably not the best comparison for you to use.

      Why build a sports car with a diesel when direct injection gives you great low end torque and it doesn’t fall on its face at 4000RPM? I drove several Miatas when I sold my GTI and there was no lack for torque low in the RPM band. It was the top end where things were a little underwhelming. (Especially compared to the S2000 I drove later.) A diesel engine would do nothing to make it a better car. VW Eos (or Golf Convertible), sure, a diesel would be fine.

  • avatar

    I happen to know the diesel rumor is just a smokescreen for the shooting brake Miata they’re working on.

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