Prior to 2008, only city and highway drive cycles were used. Three cycles were added to account for the higher diving speeds and acceleration rates, as well as temperature effects seen in the real world.
The highway fuel economy rating given for vehicles is calculated based primarily on the highway portion of the aggressive high-speed cycle and the older highway cycle. For the individual highway drive cycle used for testing, the top speed was 60 mph – lower than the typical 65 mph speed limit on many U.S. highways and freeways.
While vehicles can achieve better fuel economy at steady highway speeds instead of stop-and-go traffic, that economy begins to drop with increased speed. This is partly due to the aerodynamic drag the vehicle experiences.
The ARC created a test cycle to be used in the lab on the dyno. Test vehicles were driven at 60-85 mph steady state speeds, in 5 mph increments.