01659666

Component

A key purpose of the U.S. government fuel economy ratings is to provide precise and unbiased fuel economy estimates to assist consumers in their vehicle purchase decisions. For the official fuel economy ratings to be useful, it is important that consumers believe the numbers to be relatively reliable. This study focuses on quantifying the variations of on-road fuel economy relative to official government ratings (fuel economy gap) and seeking proper characterization of the degree of stochastic dependence between the fuel economy gap of pairs of vehicles. By using unique data reported by customers of the U.S. government website www.fueleconomy.gov,comprehensive copula based models are estimated to explore the complex stochastic dependencies (both nonlinear and non-normal) between the fuel economy gaps of vehicles reported by same person. While the Environmental Protection Agency (EPA) label estimates are similar to the average numbers reported by website customers, significant, non-linear variation is observed in the fuel economy gaps for the two vehicles across the sample. In particular, a positive dependence characterized by Student-t copula is observed between the fuel economy gaps of the two vehicles with significant dependencies in the tails of the bivariate distribution; a pair in which one vehicle achieves better (worse) fuel economy is likely to contain a second vehicle getting better (worse) fuel economy as well. The results also suggest that the strength of overall association is weak (Kendall’s Tau = 0.28). This implies lack of compelling agreement between the fuel economy gaps which could weaken consumers’ confidence in making relative comparisons among vehicles.

This paper was sponsored by TRB committee ADC70 Standing Committee on Transportation Energy. Alternate title: Analyzing Within-Garage Fuel Economy Gaps to Support Vehicle Purchasing Decisions: A Copula-Based Approach

18-00062

English

0000-0001-9969-7503

7p

2018

Transportation Research Board 97th Annual Meeting

Digital/other

Figures; References; Tables

Automobile ownership; Consumer protection; Consumers; Decision making; Fuel consumption; Government agencies; Purchasing; Ratings

Copula-based models

Energy; Highways; Policy; Vehicles and Equipment

Transportation Research Board Annual Meeting 2018 Paper #18-00062

TRIS, TRB, ATRI

Jan 8 2018 10:02AM