This paper empirically examines the factors influencing consumers' choices concerning the purchase of hybrid electric vehicles (HEVs). In addition, the paper investigates whether purchasing HEVs causes a rebound effect through which purchasers of HEVs increase their annual vehicle mileage. The results suggest that consumers who are more attentive to fuel economy may be inclined to choose HEVs. Moreover, the existence of the direct rebound effect is confirmed by the finding that the purchase of an HEV leads to an increase in annual mileage per household. Greater mileage increases future fuel cost savings from using an HEV relative to a conventional vehicle, and thus potentially leads to increased fuel cost savings that offset the extra cost of choosing an HEV. However, if the purchase of HEVs leads to a considerable increase in annual mileage, overall annual automotive CO2 emissions per household may be significantly increased by using HEVs.