Author: By BRAD PLUMER and NADJA POPOVICH

This year’s Super Bowl ads may be a sign that a shift is coming, as automakers try to persuade a skeptical public that electric vehicles are the future.

As the E.P.A. proposes rolling back fuel economy standards, here’s a look at how automakers have made their cars more efficient so far.

Several other countries have linked their fuel economy standards to the United States, so a rollback by the E.P.A. could affect rules across the globe.

Several other countries have linked their fuel economy standards to the United States, so a rollback by the E.P.A. could affect rules across the globe.

Several other countries have linked their fuel economy standards to the United States, so a rollback by the E.P.A. could affect rules across the globe.