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Old 11-21-2012, 06:33 PM   #11 (permalink)
MetroMPG
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Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,530

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 54.46 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)

Appliance car Mirage - '14 Mitsubishi Mirage ES (base)
90 day: 62.14 mpg (US)
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Quote:
Originally Posted by darcane View Post
I assume the ULEV rating is during standardized tests that may not hit the very specific requirements to engage lean burn. I haven't seen any testing, but I have to assume NOx emissions are high when it's engaged and this a likely reason it was killed.

However, these are only assumptions.
Lean burn was active during testing for the Insight to get the highway ratings it got.

It has a secondary catalytic converter (expensive) that specifically traps NOx gasses, and then catalyzes them into inert gasses at regular intervals. (Insight drivers will tell you about the 'lean burn purge'.) That's why it got the ULEV rating - even with lean burn, it emits less NOx than average.

Honda wouldn't have gone through the expense of adding this system if lean burn didn't register on the EPA tests.

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