footprint 2- car use

Looking at the carbon footprint calculator provided by the EPA in Victoria, I was surprised to discover that , despite my two cars having lowgreenhouse emissions ( 4.32 tonnes each), they had higher than average carbon dioxide emissions (51 kg) and about average nitorus oxide and hydrocarbon releases.
(you can check your own at http://www.epa.vic.gov.au/air/carecometer/default.asp)

the calculators themselves are interesting though- they only calculate certain things that they see as important. Older cars, for example, score poorly because they aren't as efficient- but the calculator doesn't take into account the energy used in creating the vehicle in the first place.
According to Wired magazine, for example, small second-hand cars are less bad than the alternatives when a car is required.

If a new Prius were placed head-to-head with a used car, would the Prius win? Don't bet on it. Making a Prius consumes 113 million BTUs [140 GJ], according to sustainability engineer Pablo Päster.... Buy a decade-old Toyota Tercel, which gets a respectable 35 mpg [6.7 l/100km], and the Prius will have to drive 100,000 miles (160 000 km) to catch up. Better yet, buy a three-cylinder, 49-horsepower 1994 Geo Metro XFi, one of the most fuel-efficient cars ever built. It gets the same average mileage as a 2008 Prius, so a new hybrid would never close the carbon gap.
---Matt Power, Wired, 19 May 2008

Using this logic, there's more environmental gain to be made by keeping a car roadworthy, rather than scrapping it and buying a new one. In fact, even an old inefficient car, destined for the scrapheap and using 13.4 litres/100km would be able to run for 80 000km before break even point. The key is to make the vehicle less disposable by treating it well, making it last and, I guess, taking it to be responsibly recycled when it finally gives up.