"I want access to as much credible information as can be obtained, in order to determine the fuel savings potential for any technology that we may introduce into our fleet."
Scott Perry, VP, Supply Management & Global Fuel Products
Ryder Fleet Management Solutions
There are many fuel efficiency technologies available to fleets but no truck could or should have all of them. Fleets must analyze the range of options and compare them against their own operations to determine which offer the fastest payback. To do this, fleets need a solid understanding of their own operation and test data on the performance of various vehicle technologies. However, it is not possible for fleets to test every device so they must rely on data from other sources.
There are a variety of test methods and each has its appropriate application. Understanding what each test method involves, its benefits and challenges, and how it deviates from real world performance will help fleets have a better understanding of how to interpret the data.
OEMs should also conduct tests on the fuel efficiency of various components to help determine which technologies to offer on their vehicles. In addition, providers of technology should invest in testing in order to better develop and validate their designs.
Basic Test Methods
There are many published test methods, but all fall into one of five basic categories:
- Computer Modeling—Computational Fluid Dynamics Analysis
This method uses computer software such as facsimile digital geothermal models to calculate a vehicle configuration’s performance. .
- Wind Tunnel Testing
Tractor/trailer wind tunnel testing uses a physical scale model of a vehicle (or in some cases a full-sized vehicle) in a wind tunnel where environmental conditions can be controlled. The size of the wind tunnel dictates the size of the model needed.
- Track Testing
There are a variety of test protocols for use on a test track. Each attempts to quantify known components of the total performance and infer that what remains is attributed to the device being tested. Assumptions and simplifications can impact test results.
- On-Road Testing
This involves evaluating a tractor-trailer on an actual highway over a statistically significant number of miles with an acceptable level of repeatability. It measures the performance of the entire vehicle and all its factors as a net total.
- Fleet Composite Evaluation
All fleets perform fleet testing if they record miles driven, freight carried, and fuel purchased. This can validate technology choices when the data is collected and analyzed.
All the test methods have value in helping to determine how to prioritize technology adoption.
Test results provide a starting point for discussion in technology investments.
- Variance among testing methods
- Extrapolation of test results
- Need to precisely attribute efficiency gains
- Use of older data
- Confusion between precision and accuracy
- Complexity of calculations and variables measured
- There is no one single correct method for fuel economy evaluation. Each method has its costs and complexity. Cost to benefit needs to be considered before purchasing a fuel saving technology.
For Test Designers and others sharing test data