PAUSE FOR A MOMENT to imagine the 1967 Dodge Charger, a first-generation fastback coupe with a 439-cubic-inch V8 engine that could accelerate from zero to 60 mph in 6.6 seconds. This powerful car weighed 4,098 pounds and got average fuel economy of just 8.4 miles per gallon. Cars were once built like that.

Now, fast-forward to today. The Obama administration has just finalized new fuel efficiency standards for passenger cars and light trucks that will require the United States auto fleet to average 54.5 miles per gallon by the year 2025. That’s more than a six-fold increase since the days of the Charger.

Last week’s announcement of the standards by the Transportation Department and the Environmental Projection Agency promises the greatest gain in auto fuel efficiency in several decades. After standards were first approved in 1975, efficiency improved, but progress stalled. The passage of a major energy bill, signed by President George W. Bush in 2007, laid the groundwork for a renewed effort. President Obama’s first round of standards set a target of 34.5 miles per gallon by 2016. Now, the second round will double the efficiency of the U.S. fleet compared with vehicles manufactured in 2008.

Not everyone will get more than 50 miles per gallon because of the way standards are calculated. But the average new car will be getting 45 miles per gallon and the new truck 32 miles per gallon. The new standards will probably add to the price of a car, but if fuel remains as costly as it is today, owners will see significant offsetting savings at the pump. (In the Charger’s day, regular gasoline cost 33 cents a gallon.)

Automakers fought these regulations for years. But now the administration has brought together 13 major car manufacturers representing more than 90 percent of U.S. vehicle sales; the United Auto Workers; and the state of California, in a grand compact. The automakers will get flexibility to innovate in designing engines, transmissions and air conditioning to improve mileage. They can also build lighter and more aerodynamic vehicles. There is also a bit of horse-trading: the law created a system of credits for meeting standards that can be used by the automakers, either banking or trading them.

No doubt, these standards are not the most efficient way to wean Americans further from imported oil and limit the emissions that contribute to global warming. But there is no political appetite for higher gasoline taxes, the most direct way to accomplish it, so the fuel economy standards are a worthy undertaking. While light-duty vehicle emissions are only about 17 percent of the of the country’s total, these tighter standards signify real progress. Taken together, the new standards mean we can move to a new age of cars that are lean and efficient, a very long way from the gas-guzzling glory of the 1967 Charger.