Dear Car Talk, I always enjoy your article, even when I think all of your cylinders aren’t firing. And this is what I thought today when reading your response in the Sacramento Bee; “Creeping is Ok for cars”, Friday, March 6, 2020. I certainly don’t have a problem staying awake while waiting for the light to turn red, so your advice won’t help me. However, I have in my lifetime noticed a marked increase in smog in the Sacramento Valley, which I believe is mainly due to automobile exhaust. This hasn’t yet caused me to give up my automobile. But trying to obey the California law, I keep three seconds distance between me and the car in front while moving. Doing this I noticed much less braking, and much less using the gas pedal. So I naturally applied this to my idling at stop lights. All this thinking I am getting better gas mileage and spewing much less carbon monoxide into the air. Now you might say my lone crusade will not accomplish much, but when you multiply this by the billions of people that read your column and religiously follow your advice, I think your response could have been better. So the question is do you think this kind of thinking is further proof that this old dog is getting too old and I should give up his car. Or should you rewrite your response to Janeen? Either way this will not stop me from continuing to enjoy your column, so please keep up the mostly good work.
Anything that helps is a great idea, but with such a wide variety of partial-zero and zero-emissions vehicle vehicles available, if you really want to help that smog problem, maybe that’s the way to go. Auto stop-start has basically eliminated any emissions in almost all modern cars when they sit at lights. Please tell us you didn’t get a diesel Passat 
How does one keep a 3-second distance from the car in front when stopped? 
How exactly do you achieve “partial-zero” 
Either you emit something or you don’t. I always thought of zero as nothing.
OK. so it’s nothing but word play. In the real world zero is nothing, and there is no such thing as partial nothing.
I understand LEV, ULEV, but partial zero is a misnomer, and an oxymoron.
The Partial Zero Emission Vehicle was a compromise arranged 20 years ago when it became apparent that vehicle manufactures would not be able to supply electric vehicles as required in the state of California. It was a government requirement 10 years before it was practical, GM spent 1 billion dollars on the EV1 project. A little bit of something is better than nothing.
Same as vodka, it is partially zero alcohol. 40% alcohol, 60% water.
The PZEV designation was so California didn’t “lose face” for requiring unicorn cars that no manufacturer could sell.
GM’s EV-1, contrary to the movie Who Killed the Electric Car, did not have enough buyers. And GM lost a lot of money on every EV-1 leased. Other car makers didn’t even really try.
It’s good to be skeptical of the EPA ratings. However, PZEV in terms of the EPA definition is much more than wordplay. PZEV certified vehicles emit dramatically less smog-causing emissions than the legal maximum for their model year. The ones on sale today meet the much stricter 2025 EPA emissions standards now. The OP mentioned smog. PZEV-certified cars were specifically designed to reduce smog through evaporative emissions as well. They have added emissions system components and the catalytic converters are different (close-coupled). They also do two additional things that conventional cars do not. They heat up the catalytic converters more quickly. Cars are their dirtiest before the catalyst is hot enough to work. They also have lower emissions in the immediate period after a car is shut down.
There is a second type of “partial zero” emissions vehicle. Hybrid cars like the Prius, Ionic, Ford C-Max actually only use gasoline as power. Here I am talking about the non-plug-in trims. Although they only use gas as energy, they do operate for a meaningful part of their running time as zero-emissions vehicles. Nothing comes out of the tailpipe. And the time they do it is important. They can pull themselves around using only the power in their batteries at slow speeds. Like when creeping along in traffic, or in parking lots. They emit dramatically less pollutants than conventional cars their same size. One added trick the Prius employs is to capture and store heat so its catalyst heats up to operating temperature much more often than conventional cars. When stopped, these cars are off. They don’t run when they don’t move except in some rare situations.
The third type of partial zero vehicles are EREVs like the Volt and the plug-in hybrids like the Prius Prime, RAV4 Prime, Niro PHEV, Outlander PHEV, BMW i3, Escape Hybrid PHEV, and many others. These can drive for a majority of the time they operate without using gas and while emitting zero emissions but can revert to a gas hybrid mode for added range when needed. Many owners only use a tank of fuel per year and the rest of the time they operate on electricity only. So litttle, the cars have a system to use up the gas before it gets stale These vehicles earn ratings as high as 133 MPGe.
The OP has good intentions. Trying to change a driving style to reduce pollutants. There are cars and crossovers that have been specifically designed for folks who want that result.
