The U.S. Environmental Protection Agency (EPA) has a list of top "fuel sippers," compiled from its fuel-economy ratings.
But none of them actually use any fuel at all.
That's because they're all electric cars.
Published on the EPA's Fueleconomy.gov website, the list includes the most efficient vehicles on sale for the 2016 model year.
Only 2016 models with certified efficiency ratings were included, so 2015 models without updated ratings were left off the list.
To compare the efficiency of electric cars to that of internal-combustion models, the EPA uses a Miles Per Gallon equivalent (MPGe) standard, where 33.7 kilowatt hours is equal to 1 gallon of gasoline.
2016 Nissan Leaf
The Spark EV is a "compliance car" built to satisfy California's zero-emission vehicle mandate, and is only sold in that state, Oregon, and Maryland.
It will soon be supplanted by the Chevy Bolt EV, which will have a 200-mile range and will be sold in all 50 states, General Motors has said.
The Volkswagen e-Golf took second place with 116 MPGe combined, followed by the 24-kWh Nissan Leaf, which is rated at 114 MPGe combined.
For 2016, Nissan is offering two battery packs in the Leaf, and both versions made the list.
The old 24-kWh pack remains standard on the Leaf S, offering the same 84 miles of range as all 2015 Leaf models.
2016 Mitsubishi i-MiEV
This version tied with the Mitsubishi i-MiEV for fourth place. Both are rated at 112 MPGe.
Other models on the list included both coupe and convertible versions of the Smart Fortwo Electric Drive, the Ford Focus Electric, and the Kia Soul EV.
Also included was the Tesla Model X, the first examples of which were delivered to customers at the end of September.
[hat tip: Brian Henderson]