Buying new cuts CO2

Even Porsche has embraced emission-cutting technology with its hybrid racer. Photo / Supplied

New cars are reducing our carbon footprint, according to Motor Industry Association figures.

Manufacturers driven by strict European and American limits are cutting carbon emissions to the bone. The European CO2 average is now 130g/km for passenger cars, and 175g/km for light commercials.

The New Zealand average was 204.2 last year, three per cent down on the year before and on track for an industry average of 170g/100km by 2015 - several manufacturers have already reached it.

The reduction is credited both to improved technology and to the increasing trend towards smaller cars. But it's having a limited effect on overall emissions, thanks to the age of the average Kiwi conveyance.

In 1992, the mean age of a New Zealand car was 9.9 years, and the fleet was regularly rejuvenated by used imports with a mean age of six years.

But when tariffs were lifted it became easier to import older cars. In 1991, the average arrival was 6.1 years old. The following year it was 6.9, then 7.1 and 7.6.

Meanwhile, the mean age of New Zealand's fleet rose to 11.6. And cars that were almost 12 years old in 2002 were built to meet the emissions standards pertaining when they were new.

Importing old cars contributes to an ageing fleet, and reduces the impact of new technology.

Regulation could make a difference. In 2008 the mean age of arrivals was 8.3 - and 7.8 a year later, after a tweak to diesel emissions rules.

Newer cars not only emit fewer noxious fumes, they boast safer technology. They also take longer to reach the scrap heap.