A little over a year ago Wired magazine asserted that if you really wanted to have a lower automotive carbon footprint, instead of springing for a new Prius, buy a good small used car.
The argument is that carbon dioxide produced while driving is only a part of the overall carbon footprint. Not often considered is the energy used (and carbon emitted) in the production of a car. Wired points out that it takes about 113 million BTUs of energy to make a Prius – or the equivalent of 1000 gallons of gasoline.
In other words, you have to drive about 46,000 miles before you have paid off this “carbon debt” associated with a new Prius – but with a used car this debt has already been paid. Similar arguments are often made regarding buildings, weighing the embodied energy contained in an existing structure, and the energy costs of demolition and construction, vs. the ongoing energy savings accrued with a new “green” building.
One way of minimizing automotive carbon debt is to buy a car that requires less energy to build in the first place. A car with less material and labor inputs, and a car that avoids energy-intensive exotic materials. A car that through extreme efficiency – a 100 mpg car, say – pays off the remaining debt very quickly.
The Very Light Car.