Yes, the various Administrations and EPA have gone too far.

Trump's Administration is expected to rescind the EPA's finding, consistent with the Chevron Deference decision at the USSC, that "carbon" (specifically, carbon dioxide) is a "pollutant."  Clearly, without CO2 we're all dead because plant life (including algae in the waters) requires it -- and without plants there are no animals.

This "finding", incidentally, was purely political.  It had zero scientific evidence as to "imminent, real and permanent" harm and Congress never gave the EPA that authority by statute in the first place.  Indeed the CO2 level inside an average house is double that in the atmosphere today -- because you exhale it, there are few plants, and air exchange with the outside is limited.  Yet you neither are materially impaired nor do you die as a result.

There is a basic principle that holds in nearly all endeavors: The first 80% of a problem -- the vast majority -- is reasonably simple and inexpensive to resolve at a given level of technological capacity.  The last 20% requires exponentially more money and complexity, rising exponentially in cost toward infinity as you approach the last few percent.

For example when it comes to gasoline engine emissions fuel injection reduces excess fuel in the exhaust (HC) by about 50% all on its own.  With closed-loop (oxygen sensor) operation and a functioning catalytic converter CO emissions are cut by 99.7% over an engine running open-loop with no catalyst.  The point is this: Nearly all harmful gasoline engine emissions are eliminated by a properly-functioning closed-loop (oxygen sensor equipped) fuel injected vehicle with a catalytic converter.  The largest single exception is during a cold start as the catalyst must get quite hot internally before it begins to function as must the oxygen sensors (the sensors have a heating element in them to speed this process.)

Serious improvements over the last 20 years, particularly with variable valve timing, have been made in this regard.  My '02 Chevy, for example, takes a minute or so for the catalyst to light off and start functioning on a cold start.  By contrast my 2015 Mazda uses valve overlap and management of injected fuel to have the sensors online in less than a quarter of the time even in sub-freezing outside air temperatures!

But once either is running in closed-loop operation it is actually quite-difficult to poison yourself with the exhaust where a non-catalytic, open loop (or carburetor) engine will do so in minutes.

So let's cut the crap on this issue: We solved this, 99+% of it, by the year 2000 and all the nonsense about "CO2" emissions are just a sop to fuel burn standards because conversion of carbon-based fuel to energy always ratably releases CO2 with the horsepower produced.

This, paradoxically, increases fuel consumption.  Why?  Because the standards are unreasonable to meet with rational levels of performance and reliability in cars, thus they're not desired and people buy trucks which get worse fuel economy (by a lot, often half or more!)

We'd be far better off returning to the 2000-2003 year standards on a ppm basis -- not "grams/mile/hp" -- which can be easily met with a catalyst and closed-loop, fuel-injected control.  This is easy with today's technology, does not require extremely expensive high pressure fuel systems, does not foul the intake because the fuel is injected into the intake ports (which prevents crankcase fume and/or EGR deposits from accumulating) which in turn leads to better running engines that pollute less and cost radically less money to produce -- and are easier and less-expensive to maintain.  Not a little either and in addition failures in a high-pressure fuel system almost always result in the instantaneous destruction of the engine or (in the case of external leaks) a serious fuel-fed fire that destroys the vehicle.

Chasing the last few parts per million is crazy; we got better than 99% of the way to zero with closed-loop, port-injected, catalytic converter equipped engines in the late 1990s and we should return there tomorrow.  Doing so would re-introduce cars to the market which instantly and wildly increases fuel economy because they're smaller and more-aerodynamic than a truck -- and if available at a reasonable price, which they will be under those standards, people will buy and drive them.  As an example the 2015 Mazda 6, a full size sedan with a nice trunk and reasonable seating for four could be had in 2014 for right around $20,000.  And that's with a high-pressure fuel system -- revert to port-injected and you take at least a thousand more off the price with almost zero environmental impact.

There's no reason we can't have that car back again -- minus all of today's "nannies" -- at that kind of price.  Yet it has airbags, ABS, reverse camera, TMPS and traction control -- and was available in both a 6 speed manual and automatic gearbox returning close to 40mpg on the highway.  Mine has a quarter-million miles on the odometer and not a single non-consumable mechanical thing has been repaired or replaced on it during that time.  These are the sort of vehicles we need in America -- affordable, reasonably fun to drive, safe, reasonably-inexpensive to purchase (and thus insure) with excellent fuel economy and reliability.  Every manufacturer can make these sort of vehicles if we stop stepping on their necks.

The second issue is more-serious and that's diesels, which really are better in truck and other "hauling" applications simply because they produce more torque down low in the RPM range where its needed in that application.  They're also more efficient and not by a little either -- since they always, except at full power output, run very lean they have no throttling losses and their thermodynamic efficiency is considerably higher.  A car that would get in the mid 30mpg range on a gas engine can reach 50mpg with a diesel.  The trade-off is that to get emissions down where we want them with those engines they need not just a catalyst but a DPF to reduce the particulates.  This has been the serious problem with them in actual service because the DPF must be extremely hot to work and thus in smaller engine applications it has been included in the catalytic converter housing.  Catalysts typically do not fail or wear out other than due to gross abuse (e.g. physical damage) but DPFs do and the catalyst is very expensive.  The result is that when the DPF fails you're looking at a bill three to five times what it should cost to replace that component because the perfectly good catalyst has to be replaced as well.  This is an engineering problem that can be solved but nobody has.  Among other approaches one could conceivably make the two as a pair with a flange to bolt them together and wrapped in an insulating blanket so as to keep them both hot -- which the DPF needs.

In heavy trucks (e.g. Class 8 semis) these two components are separate for this very reason -- the DPF is a service item (typically every 100,000 or so miles) while the catalyst is not.  This problem is solvable but nobody has taken it on, instead screwing the consumer with sky-high guaranteed maintenance expenses.  This must end.

There is also a fair question as to whether "common rail" injection is actually required to meet reasonable standards with a DPF.  I'm not sold on the claims that it is -- again, the issue is that the common-rail injection systems very expensive and if the pump fails, which they do from time to time, it almost-always throws metal fragments through the entire fuel system which turns a $1,000 pump replacement into a $5,000+ repair bill since you have to replace everything including the injectors, fuel tank and all the lines due to contamination which is otherwise impossible to remove!  In addition a "stuck" injector on a common-rail engine will, in virtually every instance, destroy the engine before you can detect the fault and shut it down.  Injection pump failure also instantly strands you when it occurs.  Again, total cost of ownership must be weighed against incremental environmental impact; when looked at this way if you can use a standard "VE" style pump and injectors plus a DPF that can be independently replaced and get 98% of the reduction of particulate emissions this is what we should do instead of shooting for the last 2% while virtually guaranteeing life-cycle cost increases that might as well include, and may include depending on the type of failure, complete engine replacement.

If the additional environmental damage from a VE + DPF setup is $1,000 over 250,000 miles but the common rail + DPF/Cat design is likely to suffer $10,000 worth of additional scheduled and emergency maintenance requirements over that same period of time the obvious correct choice is the less-complex and expensive 98% answer to the emissions problem.

It is time to bring logic back to the table; incidentally doing so essentially eviscerates any emissions or cost argument for EVs.  That is not to say people might not want them just because they do -- a Porsche or Audi doesn't make practical sense as transportation compared with a Chevy but people are free to buy what they want.

However, there is no economic (including ecological impact) argument for what we're doing today.

Put the money back in consumer's pockets and stop extorting all of us; it will have a negligible impact on the environment to do so, will bring jobs back to America in size and wildly reduce American personal transportation cost.

Oh, and revoke CARB's authorization entirely.  Transportation vehicles are inherently items that are bought, sold and used in Interstate commerce.  No regulation beyond federal can be permitted; this "waiver" crap must end right here and now.

Period.

MAKE AMERICA DRIVE AGAIN.