24/7 Wall St. pored through the U.S. Environmental Protection Agency’s annual review of fuel economy for all passenger vehicles sold in the United States to determine the most fuel-efficient vehicles in the market for the 2018 model year.
All of the vehicles on this list earned the EPA’s top ranking of “10” for being the most fuel efficient relative to other vehicles available in the market. For electric vehicles, we included only those with an MPGe of more than 70 miles to the gallon. MPGe, or miles-per-gallon equivalent, is a metric developed by the EPA to translate the fuel economy of vehicles running partially or exclusively on electricity into miles per gallon of gasoline. This provides consumers with an apples-to-apples comparison between electric-powered vehicles and their gas-burning equivalents.
Unlike conventional hybrid cars, which use batteries that reclaim energy from braking and coasting, plug-in hybrid vehicles use a rechargeable battery that can be plugged into a recharging station. These plug-in hybrid electric vehicles (PHEVs) can travel for short distances on battery power before the gasoline engine is activated. Because of this quality, PHEVs have both an MPGe and mpg rating. To determine the ranking of a PHEV, we deferred to the vehicle’s mpg rating, assuming most PHEV drivers will typically travel distances beyond what the on-board battery can provide.
Both mpg and MPGe ratings on this list assume 55% city driving and 45% highway driving.