The data from ALD, which operates a fleet of over 96,000 vehicles, shows that over the last 10 years average CO2 emissions have fallen by 24% while the rate of reduction in emissions has improved more recently, with average CO2 emissions falling by 20% in last five years alone, sitting below the UK's average of 133g/km in 2012.

ALD’s analysis of the company cars it has delivered to customers this year also reveals that 70.5% have been diesel powered, 29% petrol-engine with 0.5% being alternatively fuelled vehicles.

The fall in emissions coincides with falling driver mileage as part of a continuing focus on the reduction of vehicle operating costs, which looks set to continue in the future. ALD's research shows average mileage fell by over 2,400 miles, from 18,500 miles in the first six months of 2012 to 16,000 in the first half of 2013. Over the last decade average mileage has fallen by over 6,000 miles – a reduction of 28%.

Mel Dawson, managing director for ALD, commented: ‘Company car fleets have come a long way over the last ten years in dramatically reducing their carbon footprint and delivering significant financial savings to businesses. Carbon emissions remain very much under the spotlight and, with emissions and taxation inextricably linked, we are working closely with our customers to help them stay one step ahead of legislation.’