This procedure incorporates test cycles that produce relative fuel economy data relating to long haul, short haul, and. local driving patterns, or any combination of these and to those components developed to improve fuel economy for these patterns. The tests conducted on a specific vehicle are to reflect that vehicle's general mode of operation. The procedure is intended to be used under controlled, warmed-up conditions on a test tract or on suitable roads. A minimum of two vehicles running simultaneously is required. Test condition recommendations are provided for undertaking this engineering test. If it is necessary to conduct a test outside of these test conditions, the purpose of the test and the variant conditions should be recorded and noted whenever the results are reported.