Came across this snippet of info when I was searching.
■According to Bridgestone’s European Technical Centre, EU drivers have prematurely worn off 29.6 billion tyres and needlessly burned 3.9 billion litres of fuel in 2008 alone.This means they wasted 7.8 billion euro and released 9.2 megatons of CO2 into the atmosphere. The results came from a tyre review of 31178 passenger vehicles in 14 EU countries in 2008.
http://www.oponeo.co.uk/tyre-articles/tyre-pressure