I don't think those old trap oxidizers were known as particulate filters. They're mainly oxidizers, i.e. catalysts but they don't really trap soot. If they did, those cars that had them could never produce a smoke screen and we all know they can.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

Thats exactly what they are. It traps the soot then oxidizes it by burning it during regeneration.

Thats because nobody ever replaces them and I'd bet almost every single one has failed. Some new 2008/9 trucks that have come through the shop at Swift have a failed particulate filter. Its easy to tell since the exhaust pipe will have black soot coating the inside instead of a white light chalk-like coating. It costs $8,000 every time they have to replace one. Yes, I have driven one with a straight pipe (Filters removed for transport between shops) and its a night/day difference in performance when compared to a truck with a properly working particulate filter.

To feel good, yes. Just like with new cars though, nobody ever takes into account the emissions released and resources consumed producing, maintaining/repairing/replacing and recycling the filters since they DO have a limited lifespan. Also, the extra fuel consumed from the filter restriction and regeneration cycle does not help manufacturers meet fuel economy standards.

Well again, it's a compromise. I've read the new Jetta TDI has a particulate filter that's good for 120K miles, yet the mileage is as good as before and power is up thanks to better injection technology.

As to those old trap oxidizers, even if they were also particulate traps, like you say they were discontinued in 1987, so for a long time diesel cars did have EGR's but no particulate traps like I was saying.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

But they aren't "just now starting to show up". Mercedes has been using them for the last 9 years in europe.

Yes, I meant here in the US. Europeans have had ULSD for much longer.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

Mercedes has used them since 1985 when forced to, and they have sucked since than.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Mercedes wasn't explicitly forced to use them. They just chose to use them at the time to meet the increasingly more strict emission standards. Fortunately they later figured out a better way to meet emissions by redesigning the combustion chamber for the OM602, and the subsequent engines kept getting cleaner from there on without the use of particulate filters until just now when the technology is much more mature.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

Well if they wanted to sell diesels in CA they had to use them to 87. These days they just tell CA to go F themselves.

In the US they didn't really replace them with anything, not quite sure how they got around that.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Telling CA to go F themselves is essentially ****** themselves as CA is a big market and it's being courted again now that the technology has caught up with their requirements.

Like I was saying, better combustion chambers was the main improvement that MB made early on. The 4-valve design of the OM606 and onward helped as well, then common-rail injection came along and that helped even more.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

One other thing I wanted to mention is that the EPA pollution scale that we were talking about is the latest one for new cars and most cars from the 90's, gas or diesel, would score 0 on it. In fact even the seemingly dirty 1/10 score that for example the 2005 CDI got is no dirtier than that of a 2001 gas Camry or Audi which got the same score. Because of the late introduction of ULSD, diesels were a few years behind gassers on the EPA pollution scale but they have since caught up, and they still enjoy lower greenhouse gas emissions and better fuel economy as they always have.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

I think all car manufactures should tell CA to go F them selves. Imagine how fast Joe public would voice their displeasure to their representatives and get them to change the law when they could not buy a new car.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

It's not just CA but half of the East Coast as well. As to ****** themselves, it won't work. The EPA and CARB only mandate what is possible to achieve and I believe it's negotiated with the auto industry. I have no problem with them requiring cleaner emissions. What they should have done is require ULSD sooner so that diesels didn't have to lag behind as much. I'd like them to do one more thing: raise the minimum cetane & lubricity requirements. It'd be nice if I didn't have to additize the cat pee that they sell at the pumps.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL