The objection to diesels is soot (particulates) - very carcinogenic and implicated in the vast increase in asthma in cities (which is very real, and quite a health problem).

Typically, the main problem is NOT modern diesels, but older trucks and off road vehicles -- I've seen an old Mack truck blow more smoke in first gear on one takeoff than all my diesel (including the Volvo, with is very smoky) make in a year.

The kicker to all this (and the main reason that you will see more diesels, I think) is that GASSERS make almost as much particulates, all metal oxides (some of which are both toxic AND carcinogenic) per gallon of fuel, and they are ALL "breathable", unlke most diesel soot (that is, they penetrate deeply into the lungs and don't come back up easily).

The idea is correct, but the science is iffy. Older diesels are very polluting in terms of soot, but modern ones, especially if run on at least partial biofuels, are not.

The soot is why the 85-87 MB diesels had a trap oxidizer, and have replacement trap catalysts. All other automotive diesels have something similar, otherwise they won't pass particulates emission standards.

The standards are NOT unreasonable -- I would personally much rather take the buss and train to work, plus walk two miles to do it, than die in a couple years from lung cancer.....

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!