You sound knowledgeable. My impression was that there have been no major emissions equipment on semi trucks, namely catalytic converters, where as cars have had them since 1974.
I see that changed in 2006. I wonder why it took so long...
I recall Elon saying at the Semi event how dirty Diesel class 8 trucks were. Perhaps he was misinformed. Perhaps old trucks are grandfathered, and can be rebuilt without complying to the new rules you mentioned.
A few years back, got involved with an imported stationary winch which was converted to propane. US built, with smog equipment intact. The EPA required all kinds of testing and certs and it had to be sent back to England or be confiscated. It was a ginormous red tape hassle that was impossible to resolve without a complete cert program costing 7 figures. We sent it back.
Your understanding is not totally correct. Its true diesel trucks (and cars) do not have a catalytic converter (TWC - Three Way Cat) but thats because they only work well for petrol and natural gas engines. I won’t get into the details, but it has to do with diesel engines not targeting stoichiometric air/fuel ratios.
Because this solution was not applicable to diesel engines, they were not required. The emission limits for heavy duty trucks were achieved through different means and regulations started in 1974. 1991 saw the first tightening of particulate matter (soot) regulations, 1998 saw the beginning of NOx limit tightening. 2007 and 2010 were also big emission steps. 2007 was mostly achieved through increased EGR use and DPF filters, 2010 saw the addition of SCR systems.
This is just a general run down of EPA regulations (not CARB) but the intent was just to show the engines are far from unregulated. You can debate the regulations did not phase in fast enough and were not stringent enough (I agree) but all of these changes were fairly game changing for their time.
2027 will be another 80% reduction in NOx from the 2010 levels which is a very large step. At this point the most damaging pollution from the trucks is from the brakes and tires to put it in perspective! At the last SAE conference there was a lot of talk about measuring particulate matter from tires and brakes and how to minimize the impact as its becoming the biggest concern for health impacts.
Like a lot of what Elon says it is kind of a half truth due to missing context. New trucks are ~30x less polluting than pre 2010 trucks. The industry issue is that over 50% of the trucks on the road are pre-2010 vehicles which makes the average high. This problem can’t be solved by reducing pollution on new trucks, so industry has proposed incentivising the retiring of old vehicles as each one retired has a giant impact on reduction. Kind of a cash for clunkers proposal.
The industry proposing this may seem odd, but to tackle the problem only focusing on new vehicles only will never offset the gross polluters. Also, development of new engine technologies is incredibly expensive and the sales numbers decrease of the more expensive engines with no incentive to replace their old vehicle with the new.
So yes, the overall fleet average is pretty bad but not even EVs will help solve the problem unless the older vehicles are removed from service! Its also disingenuine to compare a new EV to a vehicle from the early 2000s when even new diesels are significantly cleaner! At least compare a modern diesel to an EV as the EV will still have an obvious advantage.
Hopefully this helps give some insight (keep in mind I left out the fuel economy regulations). It just rubs the people who have worked hard to significantly reduce the pollution from trucks the wrong way when false information is spread that new trucks are dirty and nothing is being done about it.
There is a reason I moved from ICE to EV development though as the future path is clear!
