Acceleration Performance Trends and Evolving Relationship between Power, Weight, and Acceleration in U.S. Light-Duty Vehicles

Abstract

The acceleration performance of light-duty vehicles has implications for the energy usage of those vehicles, for their attractiveness to consumers, and for the way in which these vehicles are driven. Despite this importance, many investigators rely on correlations from the 1970s for estimating performance. This paper presents a set of linear regression models for estimating acceleration times from 0 to 48, 0 to 97, and 72 to 105 km/h (0 to 30, 0 to 60, and 45 to 65 mph) on the basis of the engine power, vehicle weight, body style, and basic powertrain characteristics of more than 1,000 vehicles tested by Consumer Reports magazine between 1975 and 2010. The paper includes estimates of fixed effects for each year that capture technological improvements not directly observed in the data set and make the models appropriate for estimating performance of vehicles from many different model years. Results indicate that contemporary vehicles are better able to transform engine power into acceleration performance than were vehicles in the past with acceleration times 20% to 30% faster than comparable vehicles in the 1970s. Most of this improvement appears to have occurred before 1990, and the estimated effect is larger for 0 to 48 km/h acceleration than for higher-speed acceleration. One of the reported models was applied to historic sales and specification data for U.S. vehicles. The results indicate that new vehicles in the United States today average 8.8 s from 0 to 97 km/h, 0.9 s (10%) faster than previously thought. The trends in 0 to 97 km/h acceleration times are consistent with exponential decay toward an asymptote, and today's vehicles are within one second of the estimated asymptotic acceleration time.