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Driving an old car to save new car production emissions? | November 3rd, 2008
One argument from inefficient SUV owners is that extending the life of their beater (or even their new car) is more efficient than buying a new efficient vehicle since it takes energy to produce vehicles.

The Google Answers page that I came across resulted in many useful and credible sources of information. (Two of those sources: 1 and 2.) This led to the conclusion that about 11% of the emissions of the entire lifecycle of a vehicle are the result of production while the remaining 89% are associated with fuel sourcing, production, transportation, and use.

Take the plausible scenario where a new, relatively efficient car gets 35mpg and consider an SUV owner who gets 20mpg. How many driving miles would it take to make up the production of the small car? A little math suggests that it would take about 700 gallons of gasoline or equivalent emissions to make the small car assuming a generous 200k lifespan. That energy would be made up in about 33k miles of driving. That is, a person could buy a new efficient car every 33k miles and still come out even with an SUV driver in terms of emissions.

Verdict: Buy a new efficient car to replace inefficient (non-hybrid) SUVs -- regardless of the age of the SUV. Additionally, selling the SUV to someone who would otherwise buy a new SUV also saves the more energy-intensive production of a new large vehicle.

The same "out with the inefficient" logic also holds true for replacing incandescent (traditional) light bulbs with compact fluorescent light bulbs, even if the bulbs being replaced are new.