The stats from the Cash-for-Clunkers program sound so promising: more than 690,000 gas guzzlers taken off the road in exchange for more fuel-efficient models. About 84 percent of the trade-ins were trucks, while 59 percent of the new purchases were cars, according to Consumer Reports. The top three vehicles scrapped:

  1. Ford Explorer 4WD
  2. Ford F150 Pickup 2WD
  3. Jeep Grand Cherokee 4WD

Cash for clunkersIn exchange for:

  1. Toyota Corolla
  2. Honda Civic
  3. Ford Focus

This had to be a big win for the environment, no? Well…not really, especially if you were hoping for a cost-effective win. University of California Davis transportation economist Christopher Knittel ran the numbers:

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    • Miles per gallon for the vehicles being scrapped: 16.3 (Consumer Reports put the latest numbers at 15.8, but it’s still close)
    • MPG for the new cars: 24.8
    • Assumed miles driven per year for each: 12,000
    • Gallons of gas saved per year: 270
    • Tons of carbon dioxide saved per year: 2.7

    Assuming that the clunker would have been on the road for five more years, and given that the average rebate was $4,200, plus giving some value to the non-CO2 pollutants that are removed by the more efficient new cars, the price per ton of CO2 not released to the environment: $237.

    By comparison, the price of CO2 on the European trading market is about $22 a ton right now.

    And that’s Knittel’s best case scenario (see more on how he calculated these figures in this paper, published by the University of California Energy Institute). In reality, many of the clunkers likely weren’t being driven that much before they were scrapped, the new cars could be driven even farther given their better mileage and delightful newness, and the life of the trade-ins is more likely three or four years, not five. The actual price per ton could be closer to $500. That could buy a lot of saved trees or weather-proofed windows. 

    Which isn’t to say that swapping 16 mpg vehicles for 25 mpg ones isn’t a good thing. As one of my colleagues pointed out in an early blog post, you do get some real bang for those bucks. And of course the prime purpose of the $2.88 billion Cash-for-Clunkers program was to sell cars, and it sure did that.

    Note: The original blog post was updated at 3 p.m. on Aug. 26 with final Cash-for-Clunkers sales totals.

    Clunker photo courtesy of Flickr user ThreadedThoughtsunder the Creative Commons license.