A comparative performance study was conducted by Transport Canada’s ecoTECHNOLOGY for Vehicles program to assess the real world implications of manufacturer light weighting efforts on dynamic performance. Low rolling resistance tire technology was also tested on track to assess performance characteristics.
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Transport Canada’s ecoTECHNOLOGY for Vehicles (eTV) program tests and evaluates emerging on-road technologies being employed within Canada’s transportation system. Vehicle light weighting and low rolling resistance (LRR) tires are two such technologies currently being integrated into Canadian road vehicles. This report seeks to answer the question: what are the effects on dynamic performance through the implementations of these technologies?
Through track testing conducted at the Motor Vehicle Test Center in Blainville, Quebec, Transport Canada evaluated these technologies. Testing was conducted by PMG Technologies on six (6) vehicles selected by Transport Canada.
Vehicle light weighting refers to the reduction of a vehicle’s mass. The conceptual benefits of light weighting vehicles over model generations include increased performance, lower greenhouse gas emissions (GHG) and improved fuel economy. However, the practical benefits need to be evaluated to analyze a possible gain or loss in dynamic performance with current manufacturer implementations.
LRR tires are marketed with lower rolling resistance coefficients compared to their regular counterparts. This characteristic generally improves fuel consumption ratings, but their impact on vehicle dynamic performance requires investigation. By directly comparing track performance of an LRR tire with a regular tire we can measurably see the effects of such eco-technologies on real world performance.
Testing standards set up by the Society of Automotive Engineers, International Organization for Standardization and the Canadian Motor Vehicle Safety Standards were followed for the core investigation of this project. Although these procedures are generally conducted on a pass/fail basis and give an elementary picture of vehicle performance, this report includes results of their analysis on the complete set of data gathered to get a more comprehensive understanding of dynamic performance.
The three (3) vehicle models tested were chosen to represent different light-duty vehicle classes, as well as different drivetrain configurations. These vehicles included: Ford F150, rear-wheel drive standard pick-up truck; Acura MDX, all-wheel drive sport-utility vehicle; and Volkswagen Jetta, front-wheel drive compact sedan. The following tests were setup to assess their dynamic performance:
- Handling: Standard lateral skid pad and turning circle departure tests
- Handling: Standard slalom (transient response testing)
- ISO 3888-2:2002 Severe/Emergency lane-change maneuver
- FMVSS/CMVSS 126 – Electronic Stability Control System
- FMVSS/CMVSS 135 – Light Vehicle Braking Systems
- SAE J1491 – Vehicle Acceleration Measurement
Test results for the vehicles tested by method are as follows:
Lateral skid pad
Lateral skid pad testing was done at varying speeds to test the vehicles’ ability to maintain control at their maximum cornering limits. As speeds increased, the activation of stability control became a major factor to account for. However, testing showed no significant performance gain or loss with vehicle light weighting or the addition of LRR tires.
Turning circle departure
The turning circle (curb-to-curb) was measured using a standard low speed turning circle procedure. This was completed to measure any possible differences in turning circle diameter between the vehicles tested. No significant difference was shown between model years or tire types.
Emergency lane change
The emergency lane change maneuver ISO 3888-2:2002 was conducted to evaluate the vehicle handling and control characteristics during an emergency situation. The results of the testing showed that vehicle light weighting and LRR tires provided no direct advantage or disadvantage.
Electronic stability control
CMVSS 126 tests the performance of the stability control systems as a function of yaw. Peak yaw rate’s and yaw rates as a percentage of peak yaw after 1 & 1.75 seconds were compared in the standardized procedure. All vehicles passed the regulated minimum yaw rates in the majority of testing with minimal differences caused by light weighting and low rolling resistance tires.
Vehicle brake testing was done according to the CMVSS 135 standard. The results of cold effectiveness and high speed effectiveness were taken at both Gross Vehicle Weight Rating and Lightly Loaded Vehicle Mass. Results from both sets of testing showed that braking performance varied between non-light-weighted and light-weighted vehicle models, with no direct advantage or disadvantage being found with light weighting & LRR tires across the tested vehicles.
Slalom testing was done to observe vehicle handling characteristics. The impact of electronic stability control (ESC) became difficult to assess with its varying levels of activation. Results were then shown with and without the activation of ESC. Slalom performance did not show a consistent correlation with LRR tires or light-weighting; results showed both gains and losses in performance with light-weighting and LRR tires.
Vehicle acceleration measurement
Vehicles were tested following the SAE J1491 standard procedure. A 1000m top speed run alongside an 8-98km/h test were conducted. Light weighted vehicles and vehicles outfitted with LRR tires both generally demonstrated greater acceleration and higher top speeds.
Vehicles equipped with LRR tires and light weighted vehicles proved to perform on par or greater than their non-light-weighted/regular tire counterparts.
- Handling performance showed no significant correlation with light-weighted and LRR tires;
- Braking & slalom testing showed variable results for the setups tested; and,
- Straight line testing, including top speed and acceleration, showed improved performance across most vehicle setups.
Broad concerns for vehicle dynamic performance due to light weighting & LRR tires were not observed by eTV’s test campaign.