The Influence of Urban Trip Characteristics on Vehicle Warm-Up - Implication for Urban Automobile Fuel Consumption

This analysis estimates the ratio of the fuel consumption of vehicles as driven in the 100 largest metropolitan areas in the U.S. to what the fuel consumption of these vehicles would be if their fuel consumption rates during warm-up were those of fully warmed vehicles. Data on how, where and when automobiles are driven in the U.S. are combined with data relating trip length and ambient temperature to fuel consumption rate. Factors considered include trip length variations, geographical and hourly temperature variations and the different characteristics of work and nonwork trips. Averaged over weekday trips in the 100 largest metropolitan areas in the United States, fuel consumption is between 13% and 17% higher than it would be if fuel consumption rates during warm-up were those of fully warmed vehicles.