"So diesels, with significantly different emission profiles, are forced to comply with these emission standards designed for gas engines."

Look up which type of emission kill more people. NOx or CO? That will answer your question why things are the way they are.

"Why isn’t there the “technology forcing” for gas engine CO like there is for diesel engine NOx?"

Yes there is! It is called Hybrid Synergy Drive. It cuts down CO emission by half without comprimises. However, there is a side-benefit though -- better MPG.

Diesel can cut NOx by going hybrid as well. We shall see them soon after Gas-Electric make technology less expensive.

It's pretty annoying this discussion between Diesel and Gas Hybrid followers. Diesel is simply the only effective fuel saving technology during the past decades. Drivers habits doesn't change from one moment to another. It is still not guaranteed that Hybrid technology will not be misused to build more powerful SUV's and trucks with a green sticker.. this discussion reminds me of the early eighties in Europe when fundamental greenies have rioted. Whereas they are now simly a part of the political system. There you can talk with everyone calmly about energy technology whereas here you are confronted with many weirdos or ignorant individuals..let the Iraq war come to an end and let Fuel Prices stablize. This is all like a deja vu for a European living in the US.

“Look up which type of emission kill more people. NOx or CO? That will answer your question why things are the way they are.”

Not sure what point you’re trying to make here, but I suspect there are more fatalities from acute CO poisoning than from acute NOx poisoning. As a matter of fact, I don’t think I’ve ever heard of a case of acute NOx poisoning, but I’ve heard of plenty of acute CO poisonings.

If you’re referring to ambient levels of CO and NOx, I still have to say CO since, as I mentioned in my previous post, there are still areas of the country that are in “serious” non-attainment with the CO NAAQS, but there are NO areas of the country that are in non-attainment with the NO2 NAAQS (http://www.epa.gov/oar/oaqps/greenbk/nindex.html). It is my understanding that there are no areas of the country that are even within a factor of two of the NO2 NAAQS.

The regulatory emphasis on NOx is apparently its role as an ozone precursor. However, as I mentioned, CO is also an ozone precursor.

I have no problem with hybrid technology and think it holds a lot of promise. I agree that mating diesel with hybrid technology would be the best of both worlds. I take issue, however, with the “diesels are dirty” mantra. Diesel with particulate filters (it was mentioned that the Mercedes SUV had a DPF) are NOT “dirty” even if they can’t meet the contrived emission regs for NOx.

Why did they not make the 400 into a hybrid diesel? This is odd, they could of had a better more efficient vehicle.

Misplaced priorities? Sort of "cart before horse". We need some retail ULSD/BioD and not just in CA for clean
diesel tech(nominal NOx and 40% drop-in fuel econ)to be reality sooner. It's all about usable torque, not HP. V6,8 means double heads, cats, O2 sensors, weight, complication, etc. Turbo 4,5 cylinder diesels can get 30-50+ mpg easily. The beauty of hybrids is auto-stop, regen brakes, electric/battery accessory op. We need both in one package ASAP.

I know the debate here is about fuel economy and emissions, but how about the sticker prices of diesel vs hybrid?

For this test, because its a Benz, I am guessing the Mercedes was more expensive in this test. But, in most cases, a diesel-powered vehicle is 10 to 15 percent cheaper than a similary-sized hybrid vehicle (for cars priced between $20,000-$40,000).

Also, who knows anything about how long (how many miles) a hybrid's battery pack will last before it needs to be replaced? I have been told that most packs would need to be replaced after the first 80k-90k miles, and at a cost of $3,000-$4,000.

If true, this is a significant chunk of change, especially when an owner of a car with 80k-90k miles is often looking to trade it in or sell it in the second hand market. Tough to trade in when the buyer knows the first thing he has to do is pony up $4k for new battery pack.

On top of that, a diesel is just getting broken in at 80k-90k miles, and diesels are renowned for holding their value in the second-hand market, due to their durability and economy.

Hybrids today are being marketed to the affluent, because they have the discretionary income to pay a premium, and don't mind taking as big a loss on the send hand sale. For hybrids to become palatable to 'everyman', the cost of buying/owning a hybrid will have to come down.

"Why did they not make the 400 into a hybrid diesel?"

The price. A "clean" diesel cost almost as much as a full gas-electric hybrid. If they cost the same and get the same fuel economy which would you choose? The Pollution or The Solution?

Diesel non-hybrid would not be as smooth as a full hybrid either. When will you need to replace Diesel automatic transmission? I heard every 80k-90k miles and cost $2k-$3k plus labor. BTW, the particle filter in the exhaust system also need maintenance. How often do you need to replace that? Hey Barney, I can play FUD also.

"Also, who knows anything about how long (how many miles) a hybrid's battery pack will last before it needs to be replaced? I have been told that most packs would need to be replaced after the first 80k-90k miles, and at a cost of $3,000-$4,000."

Toyota battery pack is covered under 100k miles warrenty so, the cost is FREE. Toyota can cover 100k miles because they were tested up to 180k miles and found no degration from memory effect. Battery Management Unit computer protects the pack agreessively. The battery pack is also triple in capacity than needed to achieve that goal. Hence, it uses only a third of it's total capacity to prolong life.

For some real world info: http://www.hybridexperience.ca/Toyota_Prius.htm

Feel free to do you own research.

URSnoopy: What is "play FUD"? And why are you so angry?

I logged on to this website to learn. I had a legimate question about the lifespan of a batterypack, and the cost to replace it, before I buy a hybrid myself.

I don't know anything about the lifespan or cost to repair a diesel automatic transmission. I bought a diesel pickup in Thailand in 1994 -- with manual tranmsission -- and I have never had a problem with the engine or the tranny.

Your response to me rings of self-righteous indignation, so I am guessing you are a Prius owner. Take it easy Snoop Dog, I am not attacking your precious car. I just want to learn.

That's funny. The car magazine that performed this "test" was caught red-handed in a scandal where they helped Mercedes-Benz in doctoring a crash-avoidance test:

http://www.drive.com.au/editorial/article.aspx?id=10759

They also managed to "test" a Toyota Prius and get 32 mpg. No other magazine in Europe ever got anything worse than 40 mpg. Most of the magazines got something like 46-48 mpg, in-line with what most consumers report.

Are Auto Bild journalists simply bad drivers, or is it something more fishy?

I just saw that Auto-Motor-und-Sport (AMS) now both tested the RX400h and the Mercedes ML320CDI. The results:

0-100km/h (62 mi/h):
RX400h 8.2 sec - ML320CDI 9.6 sec

top speed:
RX400h 200 km/h (125 mi/h) - ML320CDI 215 km/h (133 mi/h)

fuel efficiency:
RX400h 10.1 l/100km (23.2 mpg) - ML320CDI 12.4 l/100km (18.9 mpg)

The AMS tests are yet another indication that the Auto Bild "test" is all a fraud. AMS is quite a serious GERMAN car magazine, so they will not be biased in favor of the Lexus. Their measurements show that the RX400h accelerates faster than the Mercedes and that it is almost 25% more fuel efficient.

http://www.auto-motor-und-sport.de/test_technik/fahrberichte/lexus_rx_300_gegen_- - - lexus_rx_400_h_zweites_programm.108823.d_ams_fberichte_techdat_td.htm

http://www.auto-motor-und-sport.de/test_technik/vergleichstests/mercedes_320_cdi- - - _mal_als_ml_e_und_r_klasse.101224.d_ams_vtest_techdat.htm

The new diesel for Mercedes Benz will be offered in the 2007 E Class, 2007 R Class and ML Class.
They will be sold in 45 states- excluding New York, Maine, Massachusetts, California and Vermont.
It will be offered next year in the 2008 GL Class, too.

When the additive "AdBlue" becomes commercially available in the US in 2007 or 2008, Mercedes will then be able to offer vehicles that qualify to be sold in all 50 states. The vehicle has a canister of this urea-based liquid. The additive is released into the exhaust system, and helps reduce the NOX emissions by 80%.