Common-rail turbo diesel: 10 percent
Continuously variable manual transmission (CVT): 9 percent
Variable valve control: 7 percent
Transmission optimization: 7 percent
Gasoline injection with turbocharger: 6.5 percent
Reduced friction within engine and transmission: 1 percent
Improved engine thermionics: 1 percent
Reduction of rolling resistance: 1 percent
Improved aerodynamics: 0 percent
Fuel-cell propulsion: 100 percent
Electric powered car: 100 percent
Natural gas propulsion: 20 percent
Hybrid (main drive combustion engine): 12.5 percent
Liquefied petroleum gas: (LPG) propulsion 10 percent
Source: Arthur D. Little
The European automakers association, ACEA, which commissioned the study, promised the EU Commission in 1998 that OEMs would lower vehicles' CO2 emissions to 140g/km by 2008. They also said they would cut emissions to 120g/km by 2012.
Such an increase to car prices would reduce overall sales and make less-profitable smaller cars more attractive. The result would be that European automobile manufacturers would suffer losses starting at the end of 2011, according to the study.
The annual added costs for the industry to reach the 120g/km level would be approximately 50 billion euros, the report shows. The additional costs to the industry would cause existing manufacturing plants to close and force new manufacturing locations to be located outside the EU, the study predicts.
ACEA president and Renault boss Louis Schweitzer confronted EU Environmental Commissioner Margot Wallstroem with the study's findings at a meeting at the end of November. The negotiations between the EU commission and the ACEA over the CO2 levels after 2008 will now go into its second round.
Henning Arp, a member of the EU environmental cabinet, confirmed that further negotiations are planned to take place during the next few weeks.
The US consultant's 240-page report examines how much it would cost to reduce CO2 emission levels to 120g/km using different propulsion technologies.
Of all the conventional propulsion technologies, cylinder deactivation would reach the highest CO2 reduction with 11.5 percent.
The use of alternative technologies such as hydrogen or fuel-cell propulsion would completely solve the CO2 problem but would be an extremely expensive option. The use of fuel-cell propulsion would cost an additional 120,000 euros per car and a car powered by hydrogen drive would cost up to 8,000 euros more, according to the study.
Costs for hybrid propulsion would add between 3,500 euros to 15,000 euros per vehicle, while the use of conventional variable valve control would only cost 150 euros to 500 euros per car.
Based on the estimated figures, the study shows that the average costs per vehicle - should the 2012 CO2 level become a requirement - would be 3,250 euros for a small car, 3,900 euros for a medium-size car and 5,400 euros for a luxury car.