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Thread: Diesel Gas Mileage

  1. #1
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    Diesel Gas Mileage

    n Europe, diesel engine automobiles are abundant and offer something like 30-40 percent better fuel mileage than their gasoline powered counterparts. They have ample acceleration and engine smoothness as well. Now that diesel fuel has low sulfur content, we assume that we will get similar products here right?

    Well, I think there's something unspoken at work here. All of the automakers produce diesel powerplants. All automakers make gasoline powerplants as well (duh). Many of GM and Fords better gas engines come from Europe. Why not diesels? First, our regulations are simply too difficult to meet. I believe that there will be a HUGE mileage penalty as a result of idiotic thngs like urea aftertreatment, air injection pumps, and yes, catalytic converters. Could it be that the advantage of a diesel may be shrunk to 10 or 15 percent as a result, necessitating longer payback periods for the fuel economy differences? We'll see.


  2. #2
    Vulture of The Western World Eric's Avatar
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    Re: Diesel Gas Mileage

    Hi Swamp,.

    I think it's another case of Detroit being behind the curve; they just haven't developed high-efficiency diesels - as BMW, VW,Mercedes and other European brands have. It's not the regulations, per se - which are objectively necessary unless we want to breath air laden with soot (and pay for the secondary costs, such as increased rates of emphysema and lung cancer, etc.). It that's our auto industry h asn't devoted the time and resources to build modern diesel passenger car engines - just as they were behind the curve on hybrids and just as it's taken them until the past five years or so to come up with "world class" four and six-cylinder gas engines.

  3. #3
    mrblanche
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    Re: Diesel Gas Mileage

    Quote Originally Posted by Eric
    Hi Swamp,.

    I think it's another case of Detroit being behind the curve; they just haven't developed high-efficiency diesels - as BMW, VW,Mercedes and other European brands have. It's not the regulations, per se - which are objectively necessary unless we want to breath air laden with soot (and pay for the secondary costs, such as increased rates of emphysema and lung cancer, etc.). It that's our auto industry h asn't devoted the time and resources to build modern diesel passenger car engines - just as they were behind the curve on hybrids and just as it's taken them until the past five years or so to come up with "world class" four and six-cylinder gas engines.
    While Detroit may not be able to make auto diesels with good mileage, Detroit Diesel has done very well, as have the other manufacturers (except Caterpillar, which has a serious problem). For the typical Volkswagen Jetta TDI to be as efficient as the Cummins in my truck, it would have to get nearly 250 mpg.

  4. #4
    Vulture of The Western World Eric's Avatar
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    Re: Diesel Gas Mileage

    We make some great light and heavy-truck engines, but as you know, these are very different animals from passenger car diesels.

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    Re: Diesel Gas Mileage

    Quote Originally Posted by mrblanche

    While Detroit may not be able to make auto diesels with good mileage, Detroit Diesel has done very well, as have the other manufacturers (except Caterpillar, which has a serious problem). For the typical Volkswagen Jetta TDI to be as efficient as the Cummins in my truck, it would have to get nearly 250 mpg.
    That is a very interesting point. I wonder why GM and Ford haven't tried to contract Cummins and Detroit to develop a small diesel engine for vehicles. The Cummins ISB and QSC don't count, as they have been installed in Dodge RAM pickups. I'm talking about something that can fit in a midsize car.

  6. #6
    mrblanche
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    Re: Diesel Gas Mileage

    You know, that's a good question. I suspect the diesel fiasco back in the early 80's more or less killed that market, although the TDI is doing well at bringing it back. I wish I could have gotten my Cobalt with a Volkswagen TDI engine.

    And that's not as crazy as it sounds. I believe the Pacer was originally designed for an engine from Volkswagen, but I may be mistaken. I know it was planned for a four, and when they had to put their straight six in it, it wreaked havoc on the design.

    Mercedes also makes large truck engines (mostly in Freightliners, since they are also owned by Daimler Chrysler). Seems like the technology should be transferable.

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    Vulture of The Western World Eric's Avatar
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    Re: Diesel Gas Mileage

    They'd have to be "clean sheet" engines - as heavy (and light) truck diesels can be (and are) loud, big and produce higher levels of pollution legally.

    Passenger diesels must be nearly as quiet as a gas engine, produce little to no visible soot/smoke, and be physically much smaller than the typical truck diesel...

  8. #8
    rc74racer
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    Re: Diesel Gas Mileage

    Unfortunately there just is not enough of market in the US to make it worthwhile for US automakers to develop diesel passenger cars. Most Americans still see diesel engines as dirty truck engines until that changes I don't think you'll see to many US passenger cars with diesel engines. You would think it would be very easy for Chrysler to do it since the have mercedes to supply engines but we still haven't seen one to my knowledge. I'm not sure but I would think ford already has passenger diesel engines since they produce cars for Europe already.

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    Vulture of The Western World Eric's Avatar
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    Re: Diesel Gas Mileage

    Quote Originally Posted by rc74racer
    Unfortunately there just is not enough of market in the US to make it worthwhile for US automakers to develop diesel passenger cars. "

    I dunno - that's kind of a chicken and egg question. In Europe, something like half the cars on the road are diesel -powered and while I agree that's at least in part a function of $4 (and higher) per gallon fuel, having driven several of these cars I can tell you there is a lot to like. A 40 mpg large sedan like the Benz E320 CDI that can also get to 60 mph in under 7 seconds and has a top speed of 140-plus is hard not to appreciate....

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    Re: Diesel Gas Mileage

    Quote Originally Posted by mrblanche
    And that's not as crazy as it sounds. I believe the Pacer was originally designed for an engine from Volkswagen, but I may be mistaken. I know it was planned for a four, and when they had to put their straight six in it, it wreaked havoc on the design.
    Wasn't it originally designed for a Wankel rotary which was to have been supplied by GM?

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    Re: Diesel Gas Mileage

    Quote Originally Posted by Eric
    I dunno - that's kind of a chicken and egg question. In Europe, something like half the cars on the road are diesel -powered and while I agree that's at least in part a function of $4 (and higher) per gallon fuel, having driven several of these cars I can tell you there is a lot to like.
    It's also helped by the fact that in most European countries diesel is taxed at a lower rate than petrol, making it something like 15% cheaper at the pump. In the UK, thanks to our revenue-hungry government (hey, wars don't come cheap!) diesel is a few pence per litre more expensive, but diesel car sales are still 36% of the total market.

    Some interesting stats at:

    http://www.greencarcongress.com/2006..._auto_sal.html

    Surprisingly low diesel car sales in Germany!


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    Re: Diesel Gas Mileage

    Vehicle aerodynamics plays a big part in gas milage. The TDI as installed in the New Beetle is rated at 42mpg highway, while the same 1.9l motor in the Jetta/Golf is only 36mpg.

    Chip H.

    Former owner: 2012 Honda Civic LX, 2006 Honda Ridgeline RTL, 2000 Honda CR-V EX, 2003 MINI Cooper S, 1992 Honda Accord LX, 1999 Mercedes ML-320, 1995 VW Jetta GLX, 1991 Mercury Capri XR2, 1981 Mercury Zephyr, 1975 Chevrolet Impala

  13. #13
    mrblanche
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    Re: Diesel Gas Mileage

    Quote Originally Posted by Dave Brand
    Wasn't it originally designed for a Wankel rotary which was to have been supplied by GM?
    Apparently your memory is better than mine on the subject!

    I did test drive one when they first came out, and I would have bought it, if the dealer had been willing to deal at all.

  14. #14
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    Re: Diesel Gas Mileage

    >>Wasn't it originally designed for a Wankel rotary which was to have been supplied by GM? <<

    It was, and that long six pushed way into the passenger compartment when they had to sub it in.



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