The dirty cost of one man's hypermiling?
 

My car failed CA emissions testing recently, and I'm confident my hypermiling had a direct relationship to the problem. When I took it in for the test, I hadn't driven the car in a month, except for a brief drive up the freeway to warm the engine up before the test.
http://i1179.photobucket.com/albums/...2012/smog1.jpg

The failure was because some of the drive cycle monitor readiness flags hadn't been set since I cleared the check engine light/malfunction indicator light in October. Since then, I'd driven 800 miles, but the catalytic converter driving cycle is 15 minutes at speeds between 60-100 kph, and I hadn't done that in 4 months.

The next day, I warmed the car up, driving it enough to add 100 miles since the test failure. The car passed smog testing. Examination of the retest shows cleaner emissions after driving the car a distance at speed. Low speed HC results had been 62, only 2 below the maximum allowable level, but dropped to 39 on the retest. Inactivity or the normal way I drive may be raising my emissions, as my HC levels are 3-15X more than average, CO levels are 1-6X the average, and NO levels are 4-7X more than average.
http://i1179.photobucket.com/albums/...2012/smog2.jpg

I drove the car 900 miles RT to/from SoCal last week, and the cat stayed lit, between 1101-1185 degrees F. When I do my normal low speed P&G, cat temps are 285-550 degrees F, too low to light the cat.

I know today's cars burn much cleaner than older cars, but I lived through pre-Clean Air Act smog conditions, and I don't like the idea of my car dumping out 3-15X the average air pollution when it's driven normally. I can only guess how bad it is with an unlit cat.

So, P&Gers like me are gross polluters. Lean burn Hondas (including some Insight Is are polluters. The pre-OBDII cars are polluters.

I'm disillusioned by the growing realization that pollution is the hypermiling community's dirt we're sweeping under the carpet.

I take issue with the thread title. You point a finger at all of hypermiling in general for the potentially negative effects of one very specific tactic. It's unnecessarily inflammatory.

How are you measuring CAT temperatures? Do you have any data previous to P&Ging that supports that it is the problem (though it does sound logical)?

I definitely agree the title is a bit dramatic when its one hypermiling technique that is the possible issue here.

I don't think its one very specific tactic... any time the engine spends off is going to let the cat cool down, decreasing its cleanliness. Turning the engine off at lights, coasting, P&G, etc.

I wonder... do modern hybrids have small cats/pre-cats designed to cope with this where non-hybrid vehicles do not? Do they have a special heat wrap or thermal insulation to retain heat between startups that may be minutes apart?

Hi Darrell,
Very interesting observation. It further points out the damaging effects of short trips in which the vehicle doesn't get hot enough to operate at its maximum efficiency. Still you have to look at the total pollution that one generates vs the mileage covered before you throw the baby out with the bath water. I know you do a lot of EOCing , maybe you could switch to engine on coasting to maintain higher cat temperatures.
all the best, L&S ( Vic )

Newer cars in general have had their cats moved up closer to the engine for a while now. I assume it is to get them to lite up quicker and retain more heat. Where as my 97 Paseo has the cat behind the engine bay, my 03 Matrix had the cat right off the exhaust manifold.

When you start a Prius up it runs for a set amount of time specifically to lite the cat. However, the new plugin Prius does not do this. If you need the power it'll kick the engine on for a few seconds and then shut off once the load is lower again. There is no insulation that I know of.

Anytime a car is driven in a way that the automotive engineers didn't foresee or is way out of the norm it has the potential to knock the emissions controls out of whack. This includes feather footing it as well.

Daox, my UG shows cat temps.

Darin, while my pollution example is P&G, there are other hypermiling pollution examples I included in this topic. The lean burn CR-Xes, Civic HF/VXes, Insight I with their high NO emissions, so sought after by some hypermilers. The hypermilers who purposely choose pre-OBDII cars so they can swap older, higher-polluting engines in and strip heavy OBDII junk out.

I wonder how that is calculated since there are no temp sensors in (most) exhausts?

If your car fails emissions testing because too much driving in lower rpms has partially clogged the cat, you only need to drive it for a mile or two in very high revvs and it will pass the testing.
But you are correct about emissions, coasting in neutral is a lot less polluting and so are OBD-II cars. And I`m not arguing here, the numbers are on the side of newer cars and that`s a fact.

Hypermiling = driving techniques.

Choice of car = choice of car.

Mods = mods.

Separate items, I would say.

The thread title is unnecessarily broad and inflammatory, something I'd expect to see in certain mainstream media, or on other forums/blogs that want to broadly bash the entire concept of saving fuel.

Note I'm not disagreeing with the ideas in your post. Just the "throwing the baby out with the bathwater" generalization of the title.

Darrell, while we have bumped heads a few times here, I truly appreciate the integrity of character demonstrated in your candid post. To reveal a problem that would affect your philosophy of conservation reflects a level of honesty I rarely see in this world any more.

As some have suggested maybe a change in technique, although I know it will directly impact your considerable mileage achievements. It is truly a dilemma.

Suggestions;

Insulate the cat to increase average temperatures.
Make sure the oxygen sensor preheating is working properly, possibly applying the preheating even before start up.
Although I hate to advise this maybe increasing the run time, with careful monitoring of the cat temp to keep it above the threshold of function.
That's very few miles over a considerable period of time, maybe a few more miles, road trip or something that would "clean her pipes" so to say.

Another way to think about it although you may not really be happy with this.

Most people drive a lot more than that, so in that respect you are already contributing much to lower overall emissions, and all cars emit much higher emissions on cold starts, so others who drive much more than yourself probably emit the same when you consider the combined effects of their short trips with numerous stops and cold restarts, something you have probably reduced dramatically or eliminated altogether.

I know my Altima would go into closed loop in about .3 mile, so it may be the best solution is to modify your driving to maintain minimum cat temp for proper functionality, combined with a few trips of some length to purge the cat itself.

I truly hope you can find a happy compromise, but your issue is a direct result of vehicle design that requires wasteful operation for lower emissions as a percentage of exhaust volume. You are reducing the total exhaust volume dramatically by minimising wasted heat energy.

It is one of the most interesting topics here I have read, keep up the good work, and don't beat up yourself. Imagine if everyone was as diligent as yourself. In the same time period I have driven many times more miles, which make me the greater polluter, if that would even make any difference to you.

regards
Mech

This is getting off-topic, but I'm curious about your comment re: "high NO emissions" of the first generation Insight.

It contradicts what I've read about the car, which was rated ULEV with the manual transmission and lean-burn.

ULEV = "emits 50% less polluting emissions than the average for new cars released in that model year."

What does this mean?

When an engine with computer emissions control is first started up, it's in "open loop" mode, where the engine runs on quite a pre-set, rich air-fuel mixture. Once it begins to warm up (including the oxygen sensor(s)), it goes into "closed loop" mode where the air/fuel mixture is set by input from that sensor, and goes from running rich to stoichiometric (14.7 to 1).

Oxygen sensor - Wikipedia, the free encyclopedia

The faster your engine goes into "closed loop" after start-up, the better for emissions & fuel economy.

SentraSE-R -

I remember the 1970's smog alerts in LA where I had to stay in the classroom. It was hard to breathe near the *beach*, no less, so I understand your sentiment.

Here is my question. What are the *total* emissions over the whole commute? The problem with this is that in order to find this out you can infer the emissions from sensor data, or you can rent or install an onboard emissions analyzer. For this reason I started this thread in 2007 :

http://ecomodder.com/forum/showthrea...ensor-316.html

I was interested in lean-burn at the time, so I wanted to know the NOx.

It's also one reason why I converted my non-heated 02 sensor into a heated one :

http://ecomodder.com/forum/showthrea...2-a-10921.html

However, that doesn't actually do much. I would need to reprogram the firmware in the ECU/PCM to take the mod into account. This is almost impossible with my car.

CarloSW2

Darin, I'm bothered by your perception of the thread title as unnecessarily broad and inflammatory. I meant for it to be controversial and attention-getting. How about a compromise change to "The dirty cost of hypermiling," "The dirty cost of my hypermiling," or "The dirty cost of one man's hypermiling?"

Re: the Insight I comment, I lumped it with lean burn cars in general, and in error. CARB barred lean burn Honda models from sale in CA in 1991 because of their high NOx levels. As you correctly pointed out, the MT Insight I was ULEV, producing 50% of the NOx emissions of normal contemporary autos.

Mech, thanks. I appreciate your compliments and suggestions very much. I do average a relatively normal ~10k miles/year with the box, with several road trips/year. My xB is a closed loop fool. Once warmed up, it's virtually always in closed loop. 98% load acceleration? Closed loop. Pulsing after a 5 mile EOC? Closed loop.

Are you really createing 15x the pollution getting double the fuel economy?

lets think rationally. The pollution you create has a weight that is directly associated with the amount of fuel you burn. The dirtier the burn the LESS weight of the pollution but you end up with carbon and aeromatics.

So your imagination is polluting.

The reality is your overall QTY of all pollution is lower, PERIOD, the amount of certain exotics that are a very small percentage of the makeup of your exhaust are larger.

I wouldn't get too cracked up over it.

NOx by itself is a non-issue.(when combined with other pollutions in a city it is) We regulate the heck out of it but it will degrade in the environment as do aeormatics and heavier emissions, heck A WATER MIST IN YOUR EXHAUST WILL ELIMINATE NEARLY ALL NOX, if you are worried.

Carbon Dioxide in of itself does not degrade a plant must convert it. I disagree with the BS of what we feel must be regulated in pollution and how in our pollution controls, especially in rural situations.

So I think you are worrying about something that isn't that important.

Afterall your exhaust and pollution levels are probably STILL 100x cleaner than the people driving 4x4s around wisconsin, including me in my cobalt during sub freezing weather on short trips. I doubt my CAT reaches operating temp on any of my trips with or without P&G in the winter and usually I don't P&G in the cold because its too hard on my battery and motor. not that it matters on short trips anyway.

If I were you I would worry more about the overall cost, does P&G cost more to you in maintenance than if you did not?

Are you REALLY polluting more than the average american driving their large 4x4 on short trips in sub zero weather?

I bet not.

If you are pro P&Ger with EOC, shut-off at stop lights, etc., chances are good that you will be running the engine 50-60% less than "normal", depending on many factors. So if the cat isn't quite hot enough and your car is polluting twice as much ppm than normal, very rough math has your overall net pollution remaining the same with a sharp reduction in CO2. If you look at the actual readings before and after in the post #1, the overall ppms of nastiness are not even close to twice as much in the first test.

I would argue that slightly higher ppms on a smog test because of monitors not being ready is far outweighed by the 50% reduction of the "m"s (in ppms) being created.

Old Mechanic and cfg83 suggest ways to mitigate higher emissions from a cool cat (pun intended). I like the idea of finding ways to mitigate the problem.

But how much of a problem is there? Does a CA smog check report fully correspond to what our cars are really doing on the road as far as emissions? The smog check is designed to measure what a car will emit when continuously running, right? But P&G and EOC mean the car is off quite a lot. So the test overestimates what actually comes from a hypermile car during an hour and a certain distance, no? The total emissions of our cars may be more than a normally driven identical car in some categories of pollutants, or it might be less, when the overall daily emissions are considered. We can't know for certain until we know a few other things about your driving. If our cars burn no gasoline 50% of the time because they are being driven through EOC, shouldn't we consider halving the numbers on our emissions reports to get a rough sense of what we might be emitting on our way to work?

Although the OP raises doubt, there are doubts about the doubts too. Seems like a perfect scenario for methodical investigation. We need test equipment and a test method.

One could test techniques and mods that attempt to mitigate or even improve overall emissions during a given commute using P&G and EOC and such. If overall emissions are less than a smog check indicates because P&G means the car is off at times, then couldn't an occasional mile or two of steady-state driving during your commute keep the cat warm enough that the overall emissions might be about the same or, who knows, maybe less than an ordinarily operating car? What mods would go along with technique (such as insulation for the cat)?

My car's cat is next to the block and attached to the exhaust manifold, so I imagine it gets hotter faster and stays that way longer, especially since I have completely blocked the grills. No cool air blows directly on the CAT. What else could I do to keep it warmer? Is overheating a possibility?

james

Sentra I gave this some thought and I am a solution oriented type of person so here goes.

You use a lot of EOC, which may also kill the preheat to your O2 sensor. If the sensor cools off enough due to the lack of power to preheat the sensor then you may be able to mitigate the issue considerably by making the preheat work during the engine off coasting portion of your glides. Keep the stove on when the engine is off so to say.

Another method of increasing the heat retention of the catalyst would be to have it ceramic coated, or to cover it with fire proof insulation and maybe an additional metal cover over the insulation. In the old days asbestos would have been ideal, but that's a nasty thing to mess these days.

The heated sensor would provide you with open loop operation virtually immediately on restart, so you would definitely improve the emissions going to the cat. It may be that your system does this already, but if not then a slight mod.

The heat retention using additional insulation would most likely vastly improve the average temp of the cat and it's ability to do it's job properly.

It seems like you have the instrumentation to verify any improvement, and I hope it meets your goals without costing you too much economy. Heck who knows it may actually help your economy but that may be wishful thinking, but if so then you would know you have maintained your sense of personal integrity and environmental responsibility.

Don't be too hard on him Metro, his concerns may actually lead us to a solution, which is a benefit to all who use the highest levels of technique. I think it might be possible to have the best of both worlds, and the maintaining of heat to the sensor is really the key to precision mixture control.

Anyway, that's my story and I am sticking to it for now. Let us know how it goes, and if I can help you can count on me, especially since us home boys on the right coast get pollution from all over the country.

:D:D:D
Just trying to inject a little humor.
Mech

Sounds reasonable to me. Thanks.

It's not personal - and as I said, I wasn't objecting to the thesis of the post at all.

Here's my concern: this thread title will be picked up in Google searches, and will be intentionally taken out of context by people who have an axe to grind against the general notion of driving to save fuel and/or modding to save fuel. It will become a source of misinformation fed to people on other sites who object to the entire concept of "hypermiling" and who won't read past the title. It's happened before. That's why I'm sensitive about a title that implies more than it should.

---

I am looking forward to reading about where you decide to go from here, Darrell.

FYI, I gave up using P&G as a routine driving technique a couple of years ago, partly because of the question of emissions which you laid out, partly because I find it tedious on anything but the shortest trips, and partly because it's arguably harder on the vehicle mechanically.

It's one reason I jumped at the chance to get the Insight: P&G levels of fuel economy without the calisthenics.

Thanks to everyone concerned with how this will affect my future as a hypermiler. If I've boycotted Exxon for nearly 23 years, I'm not about to emulate it on a smaller scale.

My hypermiling caused the CEL/MIL that I cleared with my Ultra-gauge back in October. Key-off-on toggling with the engine off and car rolling causes multiple cylinder misfire trouble codes for my car - P0301, P0302, P0303, and P0304 - the next time I turn the key on to start the car, even before the engine cranks over. The ECU apparently sees vehicle speed inappropriate with some cylinder functions, and triggers the TCs. My kill switch stopped those TCs, but a kill switch connector came loose in October, I reverted to key-off-on coasting, triggered the TCs, and I cleared them.

For those of you unfamiliar with CA smog testing, the California Air Resources Board mandates our test stations do complete visual, functional, and emissions tests. We can't skate by just on a CEL/MIL not lit, or an OBDII scan for readiness flags set.

The visual inspection checks for disconnected hoses, non-OEM or non-CARB-approved intake/exhaust/header, any alterations that might affect emissions. I ran a WAI for ~2 years, but removed it before the smog testing, because it would trigger an instant fail.

The functional test checks if the MIL is lit, and if not, if the drive cycle readiness flags are set. A lit MIL is an automatic fail. A readiness flag unset is also a fail. That's what my xB failed. I hadn't completed at least two drive cycles. One was the catalytic converter drive cycle. The other was the evaporative emissions purge drive cycle.

There's a lot of misinformation out there about passing the drive cycle monitors. Some people think you need to drive a car 100 miles. Some say it can take weeks and thousands of miles. In my case, 4 months and 800 miles of P&G wasn't nearly enough. The Scion community found the answers.

In my case, the cat drive cycle is 15 minutes of steady driving between 60 and 100 kph (~37-61 mph). I hadn't done that in 4 months! The evap cycle starts 5 hours after the ignition key is switched off, if coolant temperature is below 90 degrees. If not, it tries to start 2 hours later, etc.

I went out and drove up the nearest highway at 55 mph for 15 minutes, turned around and drove back at the same speed, and went back to the smog test station. I'd set the cat monitor readiness flag. They told me to drive 50-60 more miles, and the evap flag would set. I knew it would set overnight, so I drove home and parked my box. It passed the next morning.

Finally, we're ready to talk about CARB emissions testing, and to determine whether my driving causes more pollution than the average Scion xB.

Darin, you have the power to change the title, so go ahead. I can't figure out how to do it, probably because I can't.

Move out of California and your "problems" will be solved.

The CARB emissions test goes something like this. The smog test operator drives your car onto a set of rollers and sticks a sniffer up its tailpipe. The sniffer is connected to a test equipment computer. The op lets your car warm up. In the summer he has a big fan to blow on your radiator. I made sure to remove my grill blocks for the test.

The op enters your car's data. The computer looks up the allowable emissions for your year/make/model/engine/transmission. At some point, a drive cycle begins, where the op has to have the car in gear, driving the rollers, watching the computer screen, keeping the vehicle speed/rpm between two lines. That's where the ~1700 and ~2800 rpm test values come from.

As you can see from the scanned test results, average HC is 4 ppm at both low and high rpm, and my car initially tested 62 and 16 with 64 ppm max to pass. That's >15X normal, and 4X, respectively, with the cat lit. On the retest, my car tested 39 and 14 ppm. That's still nearly 10 times the average at low rpm, and 3.5X at higher rpm for HC.

NO isn't much better. The average car tests 16 ppm at low rpm and 18 ppm at higher rpm. My xB initially tested 101 and 89 ppm, ~6X and ~5X the average. On the retest, my car tested 105 and 74 ppm, ~7X and ~4X the average. Again, this is with the cat fully lit.

My car's CO emission numbers were 6X and 2X the average car on initial testing, and 2X and 1X the average on retest.

I've got some errands to run for a few hours, but it's clear my car has a problem. It is well-maintained. Spark plugs were replaced <10k miles ago. Oil is 5W-20W synthetic. Air filter is clean.

Mech, I'm pretty sure the O2 sensor heat stays on during coasting, since my kill switch only cuts the fuel injector common hot wire.

Tradosaurus, no, where I happen to live doesn't address the problem at all.

His concern is not passing the smog check, it is reducing his impact on the planet. Just because he might not get checked for it somewhere else, doesn't mean he isn't polluting excessively.

Kirk

Do you have the results from your last test (before this round)?

I applaud him for critical thinking but these type of threads that focus on a single point ignore the big picture.

He may reduce or increase his personal pollution but what about all the pollution upstream that got that gallon of gas in his tank? I have never seen a hard estimate but from what I was able to read roughly 100x the pollution emitted from the car itself burning a gallon of gas is created during the exploration, drilling, cracking, refinement and transport of that 1 gallon of gas to his car. This includes many types of pollution more hanous than his exhaust that go in land, sea and air. It also requires manpower and a variety of other resources that aren't fully explained or mentioned that are needed as a result.

I would stand by reducing fuel consumption is more important than slight changes in exhaust makeup.

This sounds like such a perfect test for Mythbusters, unless one of you guys have a mobile emissions testing center.

I'm still in the "FE is more important than emissions." camp myself. If you burn half as much fuel but produce twice as much emissions doing it, you're still ahead because that fuel is not having to be extracted and pumped and refined and piped and stored and shipped and pumped and burned.

brucey -

I'm definitely with SentraSE-R on this issue, but you are stating your case very well. Because SentraSE-R doesn't *know* how much he's spewing out his exhaust, he doesn't know if he is violating his principles.

CarloSW2

So a sniffer is still used? After your first post I thought that they only hooked up a diagnostic tool and looked for emissions related codes. I read that is the case in certain states and thought that Cali was one of them.
On-board diagnostics - Emission testing:
This got me wondering about how accurate pure OBD testing is, compared to physically analyzing the emissions.

Darrell, thank you for starting this discussion:thumbup: Emissions vs. fuel consumption has come up here before, but it's good to stir it every so often. I too am very curious where this goes, whether increasing your own emissions locally really would reduce global pollution, as rmay and brucey suggested. Unfortunately we still lack data, and even then we'd have to crunch a lot of numbers.

Would a smaller cat warm up faster and/or to a higher temperature? Not something you could easily replace with all the CARB restrictions, tho.

SentraSE-R -

Done.

CarloSW2

Exactly, the trouble is how would Mythbusters setup the parameters.

There is a hoard of resources that are indirectly tied to the oil by the labor force that works for the oil companies, would they be included? How do we quantify emissions into the ground or emissions that would be "other" since they aren't normally in a cars exhaust, like mercury, arsenic, cobalt and other exotics that tend to get freed.

Also our crude to fuel process goes, oil exploration, drill, extract in the US, put on the open market for the highest bidder, send 50-90% US oil overseas because it is of a higher quality than most crude. Pay the lowest bidder to refine low quality crude on antique equipment that is overseas and exempt from US regulations to make that crude usable for us in various forms. Transport back to the US (more pollution), refine further (more pollution) ship and distribute (more pollution).

I think really if we want to do the right thing for the country we need to scrap this system sending crude and gas 2-3k miles each way, seems asinine from a resource consumption standpoint, yet because of the many special interests its how we do it the wrong way and make more profit.

Ah well.

You'd expect these to return to normal with normal driving, right ?

If they don't, it looks like there's some issue with the catalyst.

CO could be due to incomplete combustion, but with excessive NOx you'd also expect high temperatures (and better combustion along with it).


Did you P&G all the way on such a long trip ?

I recall a thread where someone measured the emission when using P&G - the emissions were far higher than what he measured during steady state driving.

He then raised the question wether P&G should be renamed Pulse & Pollute ...
http://ecomodder.com/forum/showthrea...ute-14571.html

Some non-issue !
The water mist will make it into acid - I wouldn't call that eliminated.

NOx is just about the worst thing to come out of your exhaust.

Four things I would consider.

PCV valve partially clogged, easy to clean it, it sticks out of the valve cover with a hose attached. Drivers side I think. Pull it out and clean it thoroughly. Easy job, takes a few minutes. mcrews had an excellent post on how to check crankcase ventilation, put a balloon over the dipstick tube and see if the crankcase pressure inflates the balloon fairly rapidly. If so suspect PCV issues.

EGR passageways partially plugged, not enough to activate a Check engine light but enough to increase emissions.
Carbon in engine.
Cat partially contaminated due to frequent starts and shut downs.

Basically the frequency of starts and shut downs is just about the same as the worst case scenario as far as short haul short distance types of driving considered severe operating conditions in the owners manual.

If your car has an EGR system then the frequent on-off cycles mean a much greater potential for EGR passageways getting clogged with carbon build up. Low EGR flow is a principal cause of high NO emissions and will cause the timing to be retarded which will contribute to incomplete combustion.

High crankcase pressures (PCV partially plugged) will cause unburned fuel and crankcase vapors to be pushed up past the rings into the combustion chamber where they could contribute to incomplete combustion.

If it has an EGR system then I would look at the tube from the exhaust manifold to the EGR valve itself. If it is clogged, even partially then clean the tube and the EGR valve.

To clean the carbon out of the engine and the Cat, I would try an additive like techron or seafoam in the fuel and (I know you won't like this) take it out and run the crap out of it for a long time, something like 100 miles. It will kill your mileage, but might wake up the Cat and blow the carbon out of the pistons and cylinder head. Full bore acceleration runs whenever possible, wind her arse out.

If it is not to costly then have the emissions checked again to see what that has done.

regards
Mech

It is as soon as it hits cement or any number of other substances including dust, also remember the QTY of acid you will actually make, we aren't talking gallons here, think grams. A decent lifetime exhaust system will handle a couple grams of nitric.

If you don't like nitric which turns into fertalizer when it hits soil, you could have a driveway saltwater mist into the exhaust post cat, then you end up with again more fertalizer.

Or of coarse there is always the diesel solution, urea!

I disagree, the mercury vapors that come out of some poorly constructed overseas oil refineries is much worse.

Anyway...
NOx breaks down more quickly on its own than any of the other types of pollutants including CO2 which lasts longest. NOx is a synergistic compound, it can have climate benefits in the right conditions and it can also cause negatives in large cities when combined with other forms of pollution. On its own absent the exotics and aeromatics it doesn't form anything too frightening, acid in the right places is a non-issue. For example my folks dumped acid on their garden for years and had some nice blueberries and rhubarb.

Its all a matter of scale and location. I won't say its the best thing since sliced bread but many things attributed to NOx in of itself are not paticularly accurate or are exaggerated. NOx in of itself does not cause smog, other things that don't belong in the air also have to be present for that reaction to happen.

Remember too our wonderfull graph if he burns 50% less gas and makes even 25% more NOx, is he really any worse than the guy driving the pickup next to him?

At stioch your normal average modern car still makes plenty of NOx, the difference between lean and normal is splitting hairs on a 50mpg+ vehicle.
Its only the very latest that show promise with GDI and variable valves to start reducing the stoich value of NOx. All others behave pretty much per the curve with a handfull of notable exceptions, including the insight I.

To really reduce NOx we really need to reduce the number of gas guzzlers, since all cars make NOx regardless of lean or not.

Could a high performance ( as in us mpg guys) chip be made to electronically fool
the cat to be lit all the time?

If enough emphasis went into this one issue, wouldn't that pretty much end all this?

Any logical way of multipling an external plug in source of a cat pre-heat before
cold engine start?

I'm far from being Mr. Science, but thought stirring of the minds might help!

How about a custom cat with a baffle set of plates that open only one at a time,
maximizing early heat somewhat restricting the passage until heat is such that all
baffles open. Have it restrict again as rpm levels go down such as stoplight/signs;
and idling, only as safely needed.

Daox, my car's never been smog tested before. New cars get a 5 year exemption from smog testing in CA.

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FWIW, here's how I view my fuel consumption/emissions footprint. My xB has 2008 EPA estimated 26/30/28 city/highway/combined fuel consumption estimates. Since I bought my xb, I've averaged 49.4 mpg for every mile I've driven in it. I've used 590 gallons to drive ~30k miles, saving 450 gallons compared to the average xB driver. I used 55.7% of the average xB's fuel to go the same distance.

But, as seen above, I'm dumping 3-15 times the average hydrocarbons, 4-7 times the NOx, and up to 6 times the CO of the average xB, when my cat is lit, which is almost never, in local driving. Even if I use 55% of the average xB's fuel, it's inescapable logic to me that I'm producing ten times as much air pollution with an unlit cat. Preheating the O2 sensors doesn't fire the cat. I have to run the engine constantly to keep it lit.

Cats are lit by temperature of exhaust gas flow. Oxygen sensors (newer versions) are electrically heated to get them to operating temperature, which is something like 800 degrees. Frequent on off cycles allow the cat to cool below the point of proper function.
If I read correctly the XB passed emissions, on the second test, but did not function in the ideal range of what is normally expected. The second oxygen sensor in the exhaust system is there to monitor the function of the cat and the first sensor.

I Don't think Sentra had any codes except for the misfire codes he posted, which means the system should be functioning within acceptable parameters, but the range of acceptable parameters could be far higher than the ideal, which he made clear he was not happy with readings that did not closely match "ideal".

I'm not posting here to question his judgement in that area. Apparently he has a high threshold of personal responsibility when it comes to pollution, which I find to be an admirable sense of personal responsibility.

It may be that to find a balance between his extraordinary efforts at efficiency he has gone outside of the parameters of the design of emission controls that the factory provides.

The question is where is the balance of emissions and efficiency that satisfies him and only him.

It could be as simple as coasting with the engine idling, but that would affect his mileage significantly. I have tried the techniques of engine off and for the amount of work involved to me it was excessive and had some negative consequences as far as longevity of components.

Not a criticism of any one's efforts at conservation just my personal experience. It's also the reason why when I am travelling alone I usually ride my 2011 CBR, weather permitting, which has a cat, fuel injection and a feedback system like late model cars. I can get 72-85 MPG while employing mild techniques and enjoy the ride at the same time.

Again, Sentra, I hope you can find an acceptable solution. I spent some time thinking about your situation, and try to provide some suggestions based on my knowledge and experience. It does not mean I am right and everyone else is wrong, just some thoughts about possible solutions. They could be right or wrong, I hope they help.

reagrds
Mech