However, automakers run their own tests to determine mileage ratings while following EPA guidelines. The EPA only tests between 10 and 15 percent of car models on the road.
An official EPA mileage rating needs to be present on window stickers for a new car to be sold in the U.S. We were unable to reach any automakers or anyone the EPA to comment on whether that number can be published without some type of government approval that’s separate from the EPA’s testing.
If there is an approval needed, new vehicles could be put on hold if the government shutdown is long enough. We have received word that some new models not on sale yet already have their EPA numbers ready to go, so it is unlikely this will impact new-car sales unless the shutdown is months long.