Honda's New Diesel Plans


The U.S. will have the most stringent diesel emissions rules in the world when new laws go into effect next year. Automakers have already had a tough time reintroducing the diesel engine to the American market, despite improved performance and the increased gas mileage of modern diesels — often 30% better than gasoline engines. Honda today announced it has developed a new diesel engine that will meet all the new U.S. standards and turn harmful nitrous oxide into harmless nitrogen.

Mercedes-Benz is developing a similar program, but Honda says its version is superior — big shock — because it is less complicated. Even if the engine doesn’t spur new American interest in diesel engines, it will be a selling point for the rest of the world, where diesel cars are much more popular. 

[Honda Unveils Diesel System to Rival Gasoline Cars, Reuters]



I'm all for new diesel technology, anything to get better mileage. But why the heck does diesel fuel cost $.40 per gallon more than gasoline? You'd think diesel would cost less, as it requires less refining. Is it due to higher taxes on diesel? The higher price of diesel and the higher initial cost of a diesel engine wipes out any financial gain from the improved fuel economy.

I too, am all for higher fuel efficiency and anything to 'wake up' these sloth American car makers who continue to market these supposed fuel efficient V-8 and V-6's. But, I'm disappointed in Honda for only adding more confusion to the already oversaturated auto mkts. Diesel engines, no matter who makes them, are highly polluting, no matter how pro-efficient they're made to sound. Just another bandaid-fix until a real one is found.


How could you say that Diesel engines are highly polluting? Below is in regards to the VW TDI Diesel Engine. Read and learn Miria, read and learn: (The real fix is to stop driving - but no one wants to do that because it is the "American Way", not to mention, people are to fat to walk a mile.

The TDi emissions levels are among the lowest ever for Diesel powered engines. All TDi powered Volkswagens sold in the US meet so-called "Tier 1" emission limits. The TDi is often "cleaner" overall than gasoline powered cars. CO2 emissions are 25% less than a conventional gasoline powered engine. CO, HC and NOx emissions are less than previous Volkswagen Diesels. Diesel fuel has lower evaporative emissions than gasoline. Diesel fuel also requires less energy intensive refining than gasoline.

Diesel engines generally emit higher amounts of NOx and particles than equivalent gasoline powered cars, even though CO and HC emissions may be lower, and total emissions are lower due to much better fuel consumption. The current TDI Volkswagens typically emit slightly somewhat lower than the Tier 1 limits for NOx and particles (around 0.052 g/mi of particulate matter [PM] and 0.82 g/mi of NOx per EPA data), but the CO and HC emissions are far below the Tier 1 limits and well below the emissions of the equivalent gasoline engine.

Furthermore, most of the unregulated toxic gaseous emissions tend to be lower for diesel engines. For example, benzene (which is a known carcinogen) is lower in diesels by nearly an order of magnitude (i.e., factor of ten) than an equivalent gasoline engine. Diesels also tend to be significantly lower in emissions of alkenes (e.g., ethene), carbonyls (e.g., formaldehyde), and semivolatiles like polyaromatic hydrocarbons (PAHs, many of which are known or suspected carcinogens).

PM has always been regulated by mass (e.g., grams per mile). However, very recent studies show that particle number may be the more important aspect of PM emissions. According to a "real world vehicle testing report" by University of Minnesota renowned combustion particle scientists, new data show that PM number emissions from modern gasoline cars may equal or exceed diesel PM levels. It goes on to discuss gasoline PM emissions and that fact that gasoline engines may need a particulate filter much like that of a diesel. The University of Minnesota study showed that newer and older gasoline vehicles matched or exceeded diesel PM number emissions at high speed/load . It appears that diesel engines equipped with diesel particulate filters (DPFs), as many are now in Europe, will have a significant advantage in PM emissions over gasoline engines. Other recent studies are suggesting that gasoline PM is generally more toxic that diesel PM.

The emission levels from diesel engines tend to remain more-or-less constant throughout the useful life of the engine, whereas gasoline engines have many more emission-related components which deteriorate and lead to higher and higher emissions as the engine gets older.

Hmmm. First and foremost, I respect the seemingly well articulated, pro-diesel engine research data you've laid out here on CT. What a great forum it is. But, Rocco, what I'm not seeing here is any real 'big picture' look, when examining "pros and cons" making diesel cars potential front runners as the solution to the gasoline engine dilemma.
Probably your last statement regarding 'constancy' of emission levels from diesel engines vs. gas, might be the most flawed and I'll explain how if you read on. Think about it Rocco. Most of the US diesel fleet is tied up in public, private and corporate ownership of well regulated business trucks, busses and vans. The key word here is: regulated. The reason these massive fleets of diesel burning vehicles are owned and maintained by large and very profitable companies and public utilities is this. They have the capital available to maintain these vehicles to the standards of air quality we ALL hope to keep and maintain. Yes its true, diesel engines produce less CO3 than the conventional petrol engine, but the alternative smoking gun for diesels is this. Diesels, as you mentioned, burns it's fuel completely differently, whereas, the 'quick' trigger that entails diesel engines to burn its fuel all at once and without the benzene emission (onset of unleaded fuel helped reduce this emission in 1981), the relative 'unburned' fuel leftover is what the emissions industry labels - the well coined term "black soot limit". That is, what gasoline burned leaves in the forms of benzene, CO2 and CO3, diesel burned fuel leaves in the form of completely uncombusted fuel- in the form of SOOT. Particles of this 'emission', in the form of PM10 (indicating the size of the particles- (VARY LARGE))have been implicated in growing health problems, especially in larger urban hot zones where pollution levels do not dissipate quickly, or, much, if at all. One might then say, "OK, they now have the technology to install 'filters' capable of successfully capturing these particles (along with the nitrous oxides and SO2's). Well, it sure sounds nice and maybe we'll all live happily ever after eh?
Not so fast. Do you TRUST your neighbors and ALL your friends to do the very timely "diesel engine maintainence" that is demanded in order keep these diesel vehicles clean AND efficient? And do you trust your neighborhood inspection station to actually enforce the strident new emission changes that will no doubt now affect such vehicles?
In the long run, if you truly believe diesel is the new and upcoming wave of "better" alternative fuel, after very carefully weighing the PROS and CONS that might be needed if we ever are able to truly convert our billions of cars and personal SUV's, let me know. Sorry, but I just don't see it happening nor would I ever hope to breathe in a country that can't even find a way to monitor its own government better. And in case you don't believe me about smog, try a trip to Mexico City for a day or two. We can do better than that. The problem, we, as American's on the whole do not like being told what to do, when to do- or how to do it. I could trust my own self to keep a diesel well 'oiled' and clean, so to speak, but, I don't think we have the power to do it, in numbers. And thats the problem, Rocco.

First of all...why is this engine being touted as new? Honda has been selling this engine in Europe and Asia for two years. The only thing new is the funky cool catalytic converter. The improvements they have accomplished in that area certainly deserves praise compared to the lame proposals the big three automakers have been making!

Now Rocco & miria you both make very nice articulate arguments. I would like to add my two cents worth. Honda's testing of this engine yielded remarkable results. They averaged 90+ mpg over an open 450+ mile city and highway course. Don't believe it? Go to the link below. I have to believe with that kind of efficiency there cannot be much particulate matter left to pollute the air (with the new converter even less). Think of how much foreign (and domestic) oil dependency we could eliminate just by nearly doubling gas mileage with cars like this. Yes battery driven and hybrids have there place but so do vehicles like the Honda and VW, even if they are only temporary solutions. It takes baby steps to change peoples perceptions.

By the way I own one of those really large Ford Excursions. It’s a diesel. I get 17 mpg combined compared to my gas 5.4 liter Expedition. The best it ever did was 12 mpg. By my calculation that is a 30% increase in mileage. I thought it was better to save some of the earth’s natural resources the best I can. After all I use the truck to tow my camper to enjoy the outdoors with the family. When I can, I ride my motorcycle to work that only gets 45 mpg.

A couple more points. Does anyone you trust their neighbor to keep up the maintenance on their gas car or do they trade it in before the 60k mile O2 sensor, spark plug and timing belt replacement? Diesel typically uses a timing chain has and has no spark plugs to foul. It does have an O2 sensor. As a matter of fact my engine is far simpler and easier to maintain than any previous gas engine. I just change the oil every 5-7.5k miles.

Mexico City? Um almost no pollution control policy in Mexico and it is basically in a basin of mountains where wind cannot move the smog (also see L.A. County).

Nobody said we should convert current cars to diesel but certainly we could amend what we drive and get far better gas mileage with about the same number of health issues(just different ones).

Check out the data on the Honda & VW they are both viable immediate temporary solutions


Diesel and all fossil fuels are here to be used by we the people... Use them up now as quickly as possible and then you tree huggers can have all the alternatives you want. The manufacture of low emmission diesel engines for trucks large and small will end up costing so much money in lost time and revenue we will all be in a lot of trouble. look into the details of what will be asked of O.T.R. drivers stopping their trucks on the highway for waste burn-off it's a joke...........We are all getting screwed by the green movement and big oil.


Herb is an idiot.

As I know, SCR with so called "AdBlue" is on the way to the US market by MB, VW and other vehicle producer. I seams, the first car will be the MB E320 CDI in late year 2008. The trucks will / has to follow latest 2012?!? To reach the CAFE regulation (Arnold's emmision law in California) with diesel engines, are there any other possibility than SCR technic?
Regards Jost


You might as well make you're deisel engine 800+ HP to increase gas milage; besides that its fun...

sum dude

Diesel engines are by far more durable then gas engines. The longer you leave diesels running the more efficient they get.


Let's not forget the fact that diesels are the only cars on the road that can run, out of the factury, on alternative fuel. Biodiesel.
We have two diesels, a 2002 TDI and an 82, both Jettas. We love them, the mileage is great and they've been running on 100% biodiesel for years without a hitch. I just had my emmissions tested on the 82 and got a 2% opacity, the limit being 20%.
Diesels are great and when they finally stop listening to the Oil companies that don't like low fuel consumption, they might actually put out TDI-electric hybrids and go from 50mpg, what we're getting today on biodiesel, to a lot more.
Oh yeah, and Herb really is an idiot.


despite their spotty past, I think diesels are the way to go in the immediate future, especially if they can be used in conjunction with electric motors in hybrids. Biodiesel hybrid anyone?


I'm been drive a vw jetta diesel for a few years now and love it..But what I would like to buy would be a SMALL or MID SIZE diesel pickup in the U.S.A...Problem is "you can't find them here", but you can find them all over in europe !!...Are these engineers in this country sleeping...Can't they see the demand of these in the u.s.a. instead of only selling HUGE diesel trucks out here...jim


I would just like to add that, Miria comments about how unhealthy Diesel engines are is misleading and unfair when speaking about modern ( last 5 to 8 years ) diesel engines.

What I mean is modern "clean" fuel injected gasoline engines only began to get cleaned up significantly in the mid 70's or later. In fact gasoline engines are where almost all the research and design money has gone for the past 80 years or so.

Basically, the dirty diesel engine issue miria mentions applies only to "older tech Diesel engines" even though they still were/are produced until fairly recently dates back to probably the 1920's. In other words it is unfair to really even call the Diesel engine in your childs school bus a "modern" diesel engine. Newer tech Diesel engines in cars and trucks are only now coming online.

Now that we have the new low sulpur diesel fuel like most of the rest of the world as of Oct. 2006, the manufacturers can bring on the engines they've designed to use it. Addionally plant/veggie oil can be burned making them truly carbon nuetral.

Finally I think shawn point pretty well negates miria point about maintenance. All cars need to be maintained, but honestly most gasoline cars are not fully maintained either. O2 sensors, you priced them lately? My Astro van has about 5 of them, they failed after about 14,000 miles. Manual says replace at 100,000 or as needed. In other words folks, hate to burst your bubbles, but a loota things aren't as peachie as you think.


P.S. Just to add to Wades comment about Herb. Herb, sorry dude, but respectfully I think your a shortsighted dummy!!

Since when is being a real CONSERVATIVE a bad idea? Does the word POLLUTION, or LOVE CANAL mean anything to you? Even big business realized they needed to clean up their act somewhat.

To me your argument sounds like, this.

MONEY, money is meant to be spent by we the people. Saving or spending or investing money is stupid. We should just spend all the money right now.
Then when we don't have any more money left, we can just spend all the money you MONEY SAVERS would have saved.
Besides do you MONEY SAVERS have any idea how much money it will cost to save money????

And speaking of cents errrr I mean sense, it doesn't make much does it? That there is my point......

jeff e

seems we have more then one problem here boys emmisions are one thing, but think of the biggger picture , add oil and fuel resources/ reserves . arguing that diesel just doesnt solve the problem or has "badder" emmissions when the solution is just stopping driving is really just plain stupid.
Fact is our fat asses and lazy brains want a magic solution so we can keep driving our vehicles forever , any vehicle sport ute or diesel jetta. Thats just a plain delusional fantasy. We are beyond solving the addiction to oil problem. Get used to it. We are trying to stave off big trouble and diesel is the bridge to buy time to a better paradigm of energy use.
Google "peak oil" and think finite close attention to "economic collapse" crop failure starvation, war, etc etc when oil prices get too high as reserves dwindle.
diesel buys use time , for our societies to embrace "happily" a minimal fossil fuel useage mindset . A society wide paradigm shift in the way we use think about and use resources.
there will be no nuclear cars or some majic technology that will allow you to take you SUV across country 50 years from now , get use to it!! ethanol wont solve it, neither will hyrodgen. your grand kids will wonder what the heck a sport ute was they will never even see one on the road other then in a museum.they wont be going to hawaii for a summer break unless they take a clipper ship.
deisel is a "bridge" embrace it, a fuel solution is a bury your head in the sand maneuver. get real, . diesel, be thankfull for it . splitting hairs with arguments of emmisons, is laughable, there is no solution other then drastically cutting down on oil use everywhere.
peak oil....


Hey, I thought that the Euroscum all love diesels? If the commies and socialists love them then that is a good thing, right?


Diesel fuel requires 25% more crude oil than gasoline, so when factoring a typical 30% better fuel mileage, you have about a wash in acutal crude oil used.

A.J. Fleming

I own a 2005 VW Beetle TDI 6 speed, I read about fuel economy of 45 to over 50 mpg. Will those people that are getting that kind of milage please tell me the "SECRET". The best that I have ever gotten is 39.5 and average around 38.5 since new. I now have over 50K miles, all service is at an authorized VW dealership. Thanks A.J.

tdi dave

People claiming to get 45-50 mpg probably own the A4 TDI models. You have an A5 which is probably more environmentally friendly and has more power but less fuel eficient. Also you might try applying less pressure on the throttle pedal. That always helps in your fuel consumption. I average 46-49 mpg on the highway doing 70mph in my 1999 tdi jetta. I have read of people getting 55-60 mpg doing 55mph. So quit driving like you stole the car and start driving like your granny.

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