The executive branch—represented here by the Environmental Protection Agency, basically—mandated that every car manufacturer would have to have a fleetwide average gas mileage of 54.5 miles per gallon by 2025.

The Corporate Average Fuel Economy standards (CAFE to transit nerds) take the gas mileage of every car a company sells—from Yaris to Tundra, Verano to Enclave, Golf to whatever—and average it out. You want to build a gas-guzzling, smoke-pumping, V-18 for hauling a camper dragging a boat? You're gonna need to sell a hybrid, too.

Yesterday, a technical assessment report from the EPA, National Highway Traffic Administration, and the California Air Resources Board took a look at those standards and said, yeah, car companies should be able to hit them. The technology is there, or will be.