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Wayne,

there is a quite strong debate here now about diesel emissions and how many people that are killed each year by it. There are still cars being sold without filters for particulate matter, and there is only one diesel car that has technology to reduce NOx (Toyota Avensis D-Cat, only sold in the UK and Germany). I think that contributed to Toyota Prius becoming Car of the Year in Europe.

But the Toyota Prius is being challenged by new diesels with particulate filters. They still emit lots of NOx, but get fantastic mileage and emit hardly any particulate matter. See for example the 2005 Volvo S40 with a 48 mpg diesel:

http://www.volvocars.se/_Tier2/NewsE...ws/default.htm
Sorry, in swedish only. Couldn't find an english version.

Johan Erlandsson

See mileage data for my 00 Prius.
See my environmental performance (still in swedish only, feel free to ask).

I look at it this way:
- anything the diesels produce can be filtered

So there's no reason why diesels can't be just as clean as a gasoline car. But diesels still have an energy efficiency advantage.

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NOx and VOC combine with heat and sunlight to form ground level ozone which is detrimental to people with respiratory problems. 17 million americans have asthma. More NOx = more ground level ozone. Why make us suffer any more?

A Prius a day keeps the doctor away!

If you compare only standard gasoline and diesel cars, then you have a nasty trade-off today. Which do you prefer, climate change or direct health problems? I am eagerly waiting for clean diesels.

Gasoline-electric hybrids are a strong alternative today, with low CO2 emission levels and low other emission levels (I know the Prius has low other emission levels at least).

Then there is a multitude of alternative fuels that exist and are being researched upon. Here in Sweden, you can today use ethanol and biogas to propel cars. These cars get excellent CO2 and other emission levels. What is nice about ethanol cars is that they are not more expensive than gasoline cars.

Johan Erlandsson

See mileage data for my 00 Prius.
See my environmental performance (still in swedish only, feel free to ask).

CO and VOC combine with heat and sunlight to form ground level ozone which is detrimental to people with respiratory problems. More CO = more ground level ozone.

Dump the gassers. Go to diesel (no CO).

POINT: both types of engines have problems. Diesel has high NOx output. Gasoline has high CO output. Both throw out tons of soot. Like the last poster said, it's a tradeoff.

OK let's get this settled....

Diesel (even the cleanest with the exception of the veggie oil type) is WAY DIRTIER and MORE CARCINOGENIC than gasoline exhaust.

It's NOT a trade off. California would not have a ban on the registration of diesel vehicles if Diesel was cleaner - they would have a ban on GAS engine registrations.

Diesel is definitely dirtier and is NOT a long term answer or even a better solution.....it's just not.

Surely even a fan of diesel engines can see the truth in this statement?

I am not a fan of todays diesels, but I would still say it is a tradeoff. Climate change is an awful threat, and diesels are about 25 % better in that perspective.

In California though, I agree with the diesel ban. The preconditions there are special, with air that does not move enough and lots of sun, causing extreme levels of smog.

I would guess that diesel engines can be as clean as gasoline engines in a couple of years, and the ban can then be removed.

Johan Erlandsson

See mileage data for my 00 Prius.
See my environmental performance (still in swedish only, feel free to ask).

The california ban is already removed... effective 2006 when ultra-low sulfur diesel hits the market, TDIs and other diesels can be sold again.

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LARS: You keep insisting that diesel is dirtier. I'm willing to accept that conclusion, but I need some facts to back it up. Compare gas vs. diesel emissions. Actually I've already done it:
----- GAS DIESEL
NOx low high
PMs same same (they only differ in size)*
CO2 high low
CO high near-zero
HC high zero (evaporative)

As you can see, the only "flaw" with diesel is the high NOx output (same flaw as the lean-burn Insight/Civic Hybrids), and in 2006 with clean diesel fuel + cat converters the NOx problem will be fixed (same fix as the lean-burn Insight/Civic Hybrids).

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If you had asked me in 2001, I would have hated diesels as much as you. But then I actually looked at the numbers. Now if you can show me where the above analysis is wrong, I will gladly agree with you that diesels are dirtier. But I need to see the facts first.

Thanks for your patience,
Troy

* (if you don't believe gasoline engines emit Particulate Matter (PM), please go find a >100,000 mile gasoline car and rub your finger inside the tailpipe. See that black stuff? That's PM)