[Update June 20 2009
If you are considering a trade in, please use the tools linked here to see the cash value of your gas savings. The gas savings can be more valuable than a Cash for Clunkers voucher.
The final bill is linked to this post. The details below refer to an older bill.]
Following up on this earlier post, I have tried to find out how much carbon dioxide is emitted in the process of manufacturing new cars. If this amount is substantial, it calls into question the GHG benefits of replacing inefficient cars with more efficient cars.
Honda reports that it emits less than a ton of carbon dioxide producing each vehicle. To put this number in perspective, a 20 MPG car will emit 50 tons of CO2 over 100,000 miles; a 30 MPG car will emit 33 tons of CO2. The ton of CO2 emitted when producing a new car is a trivial proportion of the CO2 emitted when driving.
Consistent with Honda's claim, this WRI report says that assembly accounts for 2% of total carbon emissions from cars.
The implication: The carbon emitted to produce a new car is not a compelling reason to oppose the Cash for Clunkers plan. Gas savings will make up for the manufacturing emissions in less than a year's worth of driving.
(May 7 Update: Bill Chameides, Dean of Duke's Nicholas School of the Environment, says that CO2 from manufacture is closer to 7 tons of CO2.)
See the blog archive on the right for newer posts on Cash for Clunkers.