Enlarge / The assorted cars ready for EcoRun 2023. (credit: Blake Jennings) How do you put EPA mileage numbers to the test? You could buy a wind tunnel and a lab and start doing a massive science experiment. Or you could find 20 auto writers, put them in 20 different cars, and tell them they're in a contest of efficiency where the winner gets bragging rights. Every year, the Automobile Journalists Association of Canada does the latter.