Technical Approach to Increasing Fuel Economy Test Precision with Light Duty Vehicles on a Chassis Dynamometer 2016-01-0907
In 2012, NHTSA and EPA extended Corporate Average Fuel Economy (CAFE) standards for light duty vehicles through the 2025 model year. The new standards require passenger cars to achieve an average of five percent annual improvement in fuel economy and light trucks to achieve three percent annual improvement. This regulatory requirement to improve fuel economy is driving research and development into fuel-saving technologies.
A large portion of the current research is focused on incremental improvements in fuel economy through technologies such as new lubricant formulations. While these technologies typically yield less than two percent improvement, the gains are extremely significant and will play an increasing role in the overall effort to improve fuel economy.
The ability to measure small, but statistically significant, changes in vehicle fuel economy is vital to the development of new technologies. There are two approaches used to increase the resolution of a fuel economy measurement. The first approach is to conduct a large number of tests and to rely on Bernoulli’s Law of Large Numbers  to determine if a change is statistically significant. The other approach is to minimize the test variability by increasing test precision.
This paper will discuss the development of a Direct Electronic Vehicle Control (DEVCon) system that can operate a vehicle with high precision while testing for emissions and fuel economy on a chassis dynamometer.