Passenger Car Fuel Economy as Influenced by Trip Length

Data from the Nationwide Personal Transportation Study (NPTS) and other sources have been used to generate distributions of vehicle miles traveled (VMT), average speed, and fuel consumption as a function of trip length. Approximately one third of all automobile travel in the U.S. is seen to consist of trips no more than ten miles in length. Because short trips involve more frequent stops and a smaller percentage of operation during warmed-up conditions, nearly half of the fuel used by automobiles is consumed during the execution of these short trips.

The typical trip of approximately ten miles in length has been shown to result in a fuel economy that is equal to the average fuel economy achieved for all trips combined. NPTS data on average speed vs. trip length and General Motors data on stops/mile vs. average cycle speed indicate that the major characteristics of the trip that results in a fuel economy equal to the overall fuel economy are an average speed of 24.5 mph and 1.4 stops per mile. The composite of the U.S. Environmental Protection Agency city and highway driving cycles is 26.6 mph and 1.4 stops per mile.