New Corporate Average Fuel Economy (CAFE) and CO2 standards, as well as public concerns over the price of fuel, are driving development of technologies to incrementally improve vehicle fuel economy. The challenge of evaluating fuel economy effects of such technologies on a chassis dynamometer lies in being able to differentiate and statistically validate small changes. To meet this challenge, we have compiled more than 1,000 fuel economy data sets conducted on 30 different vehicles. Statistical models are used to determine minimum detection limits in fuel economy changes. We completed efforts to improve the repeatability of fuel economy measurements by minimizing the variability among test runs. These efforts have resulted in the ability to discern fuel economy differences of less than 1% with a 95% confidence level.
Typical programs may involve a single vehicle to ascertain fuel economy effects of different lubricants or large fleets of vehicles to quantify the impact new fuels may have on a variety of vehicles. In some programs, fuel economy deterioration effects are measured as new vehicles are driven to their full useful life. Other projects are performed to quantify small differences in fuel economy between vehicles, fuels, fuel additives, engine oils and driveline fluids.