Filed under: Biodiesel, Diesel, BMW, Ford, Mercedes Benz, Toyota, Volkswagen, USA
Popular Mechanics: "Hybrids, beware of diesels"
Popular Mechanics has issued a very interesting and in-depth article (read it here) about the upcoming diesel invasion that is arriving in the U.S. The headline quite summarizes the spirit of the article, which finds that diesels can outperform hybrids in terms of fuel economy and ease of use.The truth is that diesels have come a long way since they were popular in the '70s in the US and then forgotten when gas prices came down in the '80s. But their announced comeback is here. Offerings from Ford (the 4.4 liter V8 for the F-150), Audi (3.0-liter V6 for the Q7 and the A4), BMW (3-series sedan, which we tried here), Cadillac (2.9-liter V6) and Toyota (the 2.2-liter I4 that could arrive from Europe).
The article makes special emphasis on how clean diesel technology has arrived, specially since, thanks to low-sulfur diesel introduction, catalyst treatments can now be introduced, either with urea injection (AdBlue, by German manufacturers) or via a more complex zero-maintenance system (by Toyota). While there might be additional systems, these two are the current ones available in the market.
There's also a special mention on the durability of diesel engines, which can clock 250,000 miles easy thanks to diesel's lower coefficient of friction, which lubricates when fueling the car (biodiesel is claimed to be even better for that purpose, but note that biodiesel is never mentioned in the PM article).
To end the article, there is an interesting comparison between a Toyota Prius and a Polo Bluemotion (except that the prices weren't fair. A Prius costs from about 25,000 EUR in Germany, whereas the VW costs 16,300 EUR) stating that the small diesel was quite better in terms of mileage than the hybrid. Nevertheless, small diesels aren't arriving - yet - stateside.
[Source: Popular Mechanics (h/t to Matt for the tip), Auto-Preise for car prices in Germany]
Reader Comments (Page 1 of 2)
Salt Water Sound 12:51PM (12/28/2007)
I'm seriously interested in the new Audi 3.0 TDI but I've been looking for a decent analysis of CO2 emissions from Biodiesel and haven't found anything yet. Even with Low Sulphur fuel, are diesels still "dirtier" than gas engines? Is their better fuel economy enough to offset the emissions?
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Xavier Navarro 12:58PM (12/28/2007)
Just to give you an orientation, the figures for the car you said, at least in the UK are the following:
Engine/Trim SE 3.0 TDI 239 HP 6 speed
Combined fuel consumption: 40.9 mpg (imperial, about 34.5 mpg US)
CO2-Combined emissions: 183 g/km
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James Bowe 1:15PM (12/28/2007)
Why is there so much talk of the comparison between diesel's and hybrids? Why not cut out all the hype and make a ...(gasp)... diesel hybrid? Now you're talking big-time mileage. Stop these silly comparisons. Let's keep it simple. A car is a car. How far does it go on a gallon of fuel?
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Mike Z 1:43PM (12/28/2007)
From everything I can tell with my discussions with auto engineers, a Diesel Hybrid is actually a *VERY* hard thing to do. The problem is that current gas hybrids rely on the fact that a gasoline ICE engine can rapidly start/stop when warmed up. Diesel engines have a very long way to go before they can be stopped are restartable quickly and reliably.
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Steve 1:54PM (12/28/2007)
That's just conventional, Toyota-style thinking with regard to hybrids. The reality is that a diesel-electric series hybrid is a really good idea--it's no coincidence that GM included the possibility of a diesel range extender in its E-Flex plan.
With a series hybrid, the diesel engine (a range extender, really) can run at constant load (e.g., maximum efficiency) to recharge batteries while the electric drive moves the wheels.
The only major obstacle to this is the problem of cleaning up diesels, something that results in price premiums of a few thousand dollars over non-diesel counterparts (the cost of diesel engines is also higher than that of gas engines, due to greater resiliency needed for the high-pressure diesel combustion). Ultimately, though, with diesels being heavily worked on by automakers, it's only a matter of time before that kink is worked out as well.
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Tim Russell 1:55PM (12/28/2007)
Mike Z to add to what you said expense. Diesel engines cost more than gas engines. Add the cost of a hybrid system on top of the cost of a diesel and you'll pay a very large price premium, you'll get great MPG but you already paid on the front end.
The GM E-flex drivetrain would allow for a diesel and side step the start/stop because it decouples the engine from the wheels. No start/stop problem as the engine would start once, charge the batteries and then stop.
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Whopper 2:46PM (12/28/2007)
A hybrid uses an engine to drive a generator to charge a battery which discharges that electrical energy to an electric motor which converts that into mechanical energy. That energy is used to drive the vehicle via a transmission of some sort. At each step in this process there are efficiency losses. In two like vehicles with the powertrain the only difference, logic says the diesel must outperform the hybrid.
To those upset regarding the EPA rejection of California’s request for a waiver, note that the PM article observes that high-mpg European diesels are not available in the US because they don’t meet California’s regulations. Perhaps those on the west coast don’t know everything afterall.
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MH 4:03PM (12/28/2007)
Mike Z,
The start/stop feature in a modern diesel is not an issue, maybe it requires a bigger battery. For example, the BMWs 120d 320d already have that function as a standard and they are very popular in Europe.
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mike 4:25PM (12/28/2007)
The diesel-hybrid price myth. Seems Peugeot hasn't yet heard this one yet.
And Whopper, stop telling whoppers, the electric engine is still the most efficient powerplant on the planet. And an electric hybrid is powered by Cheap electricity, especially if powered in off-peak hours. An electric / electric-diesel are still the best options.
And then there is the NanoTube Battery breakthrough.
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Mike Z 4:39PM (12/28/2007)
BMW's Stop Start is only used when the car is stopped and in neutral. It cannot be used to stop-start operation while driving (ie coasting to a stop), the reason cited above---the issues with quickly restarting a diesel.
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fawgcutter 4:54PM (12/28/2007)
I thought Honda was producing a diesel with zero maintenance system:
http://www.autobloggreen.com/2006/12/04/honda-is-developing-a-diesel-v-6-for-suvs-and-vans/
If all auto companies will get off their "not invented here" high-horses and cross-license more frequently (or be allowed to), there will be more options for solutions.
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Mark 5:56PM (12/28/2007)
a polo is much, much smaller than a prius. comparing them doesn't make any sense.
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Chris M 6:52PM (12/28/2007)
Diesels have 3 problems: higher initial price than petrol engines, starting in cold weather, and emissions. Not much can be done about the higher initial price other than pointing out the overall savings in the long run. The newer Toyota Hybrid models have a thermal storage system to prewarm the engine before starting, diesels would get a big benefit from that technology. I'm glad to see reduction in diesel emissions, though they are still higher than the best hybrids.
"Whopper" badly misunderstood hybrid operation. The only time a hybrid charges the batteries is when there is excess power available, it does not require all the power to be routed through the batteries. While energy conversion does have some losses, hybrids more than make up for that loss with several energy saving techniques not available to non-hybrids.
While "mild hybrid" designs would not be suitable for diesel engines due to the extra starting torque required, the "full hybrid" designs have much more power and torque available and would have no trouble with autostarting.
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john1701a 11:11PM (12/28/2007)
Bin-5 is the emission rating those new diesels will offer. That's dirtier than the typical gas vehicle and embarrasing compared to the SULEV and PZEV rated hybrids available.
It's a step backward embracing diesel when the result is an increase emissions of NOx and PM.
Why aren't the automakers offering diesel systems that reduce SMOG pollution too?
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Lad 12:20PM (12/31/2007)
People: The auto companies have planned and invested in bringing diesels back to America for some time now. And, this is what you see...their attempt to save their investment with lots of PR hype. Diesels will return to their same old dirty selves as soon as they accumulate high mileage. ICEs, either gasoline or diesel powered, don't make sense to use and never have from an efficiency standpoint. Neither is more than 25% effecient at the rear wheels. For this very reason, they will be replaced by electric vehicles in the future because we have an oil shortage and BEVs are much more efficient and have very few local pollution issues. ICEs and burning fossil fuel is only an interum solution until BEVs become more widely available. So enjoy the noise, pollution, and smells while you can as the era of ICEs will soon start to be phased out. And, don't bother to save ICE cars in barns, fuel will be far too expensive to drive them.
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wxman 12:32PM (12/31/2007)
With all due respect, as an air quality forecaster and air pollution meteorologist, I disagree with the "diesels are dirty" opinions expressed in this thread, at least when considering these "clean diesel" vehicles discussed in the Popular Mechanics article.
Everyone seems to focus on the higher PM and NOx emissions of diesels, but neglects their lower HC and CO emissions.
HC emissions (both direct and indirect) are a much more important in ground-level ozone/urban smog production than NOx.
In addition, HC emissions oxidize in the atmosphere to formaldehyde (a potential carcinogen) and ultimately ultrafine PM ("PM0.1"). Most ultrafine PM in the atmosphere is secondary in nature (i.e., formed from gaseous precursor emissions).
Furthermore, PM emissions from particulate filter (DPF) equipped diesel vehicles (i.e., all new diesel vehicles sold in the U.S. since Jan 2007) have PM emissions that are virtually indistinguishable from ambient levels (both mass and particle number).
In my opinion, we need to phase out gasoline as a transportation fuel if we want to make significant reductions in urban smog.
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Guenther 12:49PM (12/31/2007)
The main reason why diesel-hybrid hasn't been widely looked at is because of diminishing returns- diesels are much more efficient than spark ignition engines at part load, so a large part of the improvements to be had from a hybrid are negated. Regenerative braking is certainly still valid.
Cold starting is not a problem- at all. A slong as the proper winter blends are used, many, if not most diesels these days will start un-assisted at -30F.
Emissions aren't as low as SULEVS or PZEVS, but gasoline regs don't even test PM. HCCI (similar to the MB "Diesotto") may eventually prove a better answer than diesel.
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Emil 3:33PM (1/01/2008)
So, whom that vehicle must beware of ?
http://www.autobloggreen.com/2007/05/19/australia-hino-hybrid-introduced-completes-24-hour-endurance-t/
Dear s10, the advantages of diesel over gasoline are :
1. Diesel vehicle use less fuel.
2. Most of diesel vehicles can use B20 while gas ones - only E10 - I mean higher percentage of biofuels without modification.
There are of course disadvantages too, but I still think there there is a need to move in all directions. Still hope to see Peugeot Diesel hybrids soon.
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s10 3:53PM (1/01/2008)
Diesel hybrids is completely possible, actually Toyota builds and sells them already thru their HINO heavy vehicle devision.
Cars equipped with Diesel engines don't have to cost more then the same car with a gas engine. Actually in Europe they're often offered for exactly the same price.
My problem with diesel is that it is still using an oil product in order to run when we need to invest in alternative energy sources, especially electric, to get rid of oil based engines all together.
The best way to help with the innovation is by buying hybrids.
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Bill 3:55PM (1/01/2008)
I'm enthusiastic about diesels, but note they are coming slowly to the U.S.
Affordable VW diesels are rumored to be delayed from spring to late, late summer of next year (Labor Day?)
And Asian/U.S. diesels are at least a year behind VW.
I like that diesel Accord, but realistically it's a good 18-24 months away.
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