I'm afraid I may have rushed into my descision as to which hybrid to buy. I purchased a 2005 Honda Civic Hybrid mainly because I was concerned with MPG, and after doing some research here on Green Hybrid, saw that the average real MPG between the HCH and Prius were nearly identical.

However, I did not notice the Smog Index until after purchasing the vehicle. The smog index of the 05 HCH is 0.9 on a scale from 0 to 3, 0 being the least polluting. I (along with many other HCH owners, apparently) was surprised to see my ULEV 05 HCH has a higher smog index value that the average new car, 0.8.

At the time of purchase, I was strongly considering waiting for the 06 HCH, or getting a Prius, but was convinced to opt for the 05 HCH instead on account of price and availablility in my area.

But now, after seeing that both the Prius and the 06 HCH have SULEV ratings or better, I'm feeling very sketchy about my decision.

Can anyone explain how an 'efficient' hybrid can be more polluting than your average car with a standard ICE engine?

Anyone else having the same concerns?

 

The reason is that it uses "Lean Burn" technology, and when in that mode (very fuel efficient) it produces more smog forming pollution. Honda dropped their non-hybrid lean burn car, and I think they had to drop it from the HCH to get the SULEV-II rating. It activates during steady-state cruising when the load is low enough. I think Honda should have made the HCH clean in all states, like the Prius because a lot of the hype of Hybrids is that they pollute less... and they are the 'cleanest' company, supposedly.

 

I guess you're not in one of the PZEV/SULEVII/BIN2 states or you picked up one of the few ULEV/BIN9 rated HCHs sold in a PZEV state. In California (and some of the northeast states) many HCHs are rated partial zero emissions. To accomplish this, the PZEV HCHs do not have lean burn capability and have a different catalytic converter/emissions system than the ULEV/BIN9 HCHs. Another perk for PZEV HCHs, other than reduced emissions, is a 10 year/150,000 mile warranty on most of the IMA/emissions components, unavailable on ULEV/BIN9 HCHs. Look on the bright side: you're still consuming less fuel, voting with your dollars to further hybrid technology, and that's definitely a start.

See this thread for more . . .

https://www.greenhybrid.com/discuss/...lean+burn+PZEV

 

Do you have a choice whether to activate lean-burn ?

 

No, I'm pretty sure it's like VCM, it just comes on at certain operating conditions, like steady highway cruising.

 

So for all the tech gurus out there... let me see if I understand all this correctly: I live in California. I bought my 2005 HCH here. Thus I have a PZEV with the extended warranty 10 yrs, 150,000 miles that covers the emissions parts of the car? Meaning.... if I don't pass a smog check in under 10 years or 150,000 miles I can make Honda fix whatever is wrong? (Forgive the girly naivete... blame it on the blondeness)

Since I have a PZEV I do not have capability to 'lean burn'. Is that correct? Also, what is lean burn? If I understand it correctly when a ULEV is in a constant cruising speed (I guess anything between 40 and 50 mph) on cruise control... the car's system begins to burn even lower fuel than in MY PZEV, correct?

However, as I can see it my car is nearly the best thing I could have short of a full-electric engine or a bicycle plus I have extended warranty on these low emissions. Since I've now learned the driving tips on maximizing my fuel economy and now get anywhere from 53 to 61 mpg I feel on top of the world in terms of my choice and it's effect on the Earth and my pocketbook.

Correct me if I understood any of that... you gotta give us a break with all the acronyms and hyphenated terms... sheesh! ehehee

 

Its really very simple:

The HCH W/ the CVT or MT is either ULEV or PZEV. IMHO, I LOV the HCH w/ the CVT and the PZEV.

...Sorry, couldn't resist

 

That's basically all correct as far as I am aware of. The other difference between the ULEV and PZEV is that they have different catalytic converters as well as different gas tanks that make for no evaporative emissions when the car is off, and hence the Partial Zero Emissions Vehicle category. There's also different grades of fuel in areas that will also affect how a vehicle is rated in terms of emissions in various states.

Lean burn is when there's more air in the cylinder than there normally should be for ideal combustion. Normal ratios of around 14 parts of air to 1 part of gas is how most cars operate most of the time, but some Honda engines can operate at 22 parts of air to 1 part of gas. It has the side effect of increasing the temperature in the cyclinder and that causes more NOx formation that has to be cleaned up by additional catalytic filter devices.

 

I don't mean to hijack the thread, but I'm going to post something I wrote in another thread regarding the warranty on PZEV HCHs.

If your car's designation is AT-PZEV, you have a factory warranty that covers the IMA system for 15 years/150,000 miles (the battery itself is warrantied for 10 years/150,000 miles). This is a Honda warranty that doesn't come from the dealership or a third party. More over, it doesn't cost anything.

With that said, the AT-PZEV warranty is not a bumper to bumper warranty. It covers major emissions related parts, the most important being the IMA components.

Here's a link to the original warranty page on the Honda Owner's Link website. You can check what warranty comes with your car.

http://www.ahm-ownerlink.com/Documen...t/apl27540.pdf

If you are PZEV rated, you don't have the lean burn feature. Check out wikipedia's definition of lean burn:

http://en.wikipedia.org/wiki/Lean_burn

Basically, what Schwa said.

 

Well now, you bring up something I have wondered about.

My Prius has a pzev sticker, but it was bought and resides in NM, which is not a CARB state. Does the extended warranty apply ? I have always thought no, since low sulfur gasoline is a requirement for cat longevity, but maybe regs apply here instead of logic ?

lamu, no misconceptions in your post. Be aware (and happy) though, that the emissions warranty also includes the battery pack out to 150K miles.