An independent study by FEV GmbH found that timing belts in automotive timing assemblies better reduced CO2 and gave more ride comfort than did chains. In a 1.6-liter gas engine, a belt drive reduced fuel consumption by more than 1%, saving up to 1.5 gm of CO2/km.
Belt-drive-system suppliers Dayco, Gates, and ContiTech commissioned the study to determine the potential friction advantages of belt-driven timing assemblies. Tests on a straight-four gas engine showed a belt drive reduces engine friction by 0.04 bar compared to a chain drive. That represents a 30% friction advantage.
Testers recorded a 1% fuel savings at a maximum load. When driving at speeds of 20 to 30 mph, as are common in urban traffic, the reduction in fuel consumption exceeds 1%. As you might expect, lighter vehicles save more fuel.
FEV found the lower fuel consumption reduces CO2 emissions of a 2,500-lb medium-weight vehicle by as much as 1.5 gm/km. For a vehicle weighing in at 3,600 lb, CO2 emissions are down by 1.3 gm/km.