Average new car CO2 emissions have dropped by 33g/km in the past decade, and stood at 158g/km at the end of 2008, according to the latest figures from the Society of Motor Manufacturers and Traders.
These figures were revealed in its latest New Car CO2 report. The first, dating from 1997, saw average tailpipe CO2 emissions of 189.8g/km.
A combination of maturing emissions control technologies and the long term rise in diesel sales are cited as drivers for the reductions. According to the SMMT, UK diesel sales stood at just over 43 per cent in 2008.
It also found that sub-120g/CO2 products were increasing market headway, taking 11 per cent of 2008 sales, triple that of 2005.
However, the organisation warned that the decline in the world economy could result in the lives of older, more polluting cars being extended by owners keen not make big financial investments in new vehicles, which could feed through into a slowing of overall car-based CO2 levels. The SMMT also warned that rises in diesel prices could make higher CO-emitting petrol models more popular, and this could have a negative impact on total emission figures.
Conversely, it suggested one aspect of the recession which could have a positive impact on CO2 emissions related to the huge declines in new car sales at the tail end of 2008. Bigger, often higher emitting vehicles were hit particularly hard, although it noted the largest improvement in emissions came from the upper medium segment, which saw a 4.8 per cent improvement, helped by the spread of diesel engines into premium models.