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Making Cars More Fuel Efficient

Technology for real improvements on the road

This report provides a technical analysis of why vehicles perform better in fuel economy test
procedures than they do in actual operation on the road. It examines how the gap between test and
“on-road” emissions can be closed. A variety of technologies are examined that, whilst they show now
gains in the tests used to certify vehicles for sale, could improve fuel economy and reduce CO2
emissions in the real world. Manufacturers have little or no incentive to introduce these technologies
although they could be used to cut emissions by over 10%. The practical information presented here
should assist policy makers in identifying technologies and other strategies such as driver training to
promote fuel efficiency on the roads and provide incentives for the uptake of the relevant technologies.