nder the Obama administration’s pollution-cutting mileage and emissions rules, the fleet of new cars sold in the United States in 2025 must average 54.5 mpg, with the fleet growing cleaner each year on the way to that strong standard. But a new report from the Environmental Protection Agency demonstrates how loopholes are letting most carmakers get away with lower annual performance and still be considered in compliance.

The manufacturers successfully demanded the loopholes when they negotiated the standards with the administration. The loopholes let the companies undercut the rules’ strong targets and turn out cars and light trucks that increase pollution. It’s akin to a doctor telling you: “Go ahead and smoke, as long as you go on a diet.”

Here’s how the loopholes work:

■For each vehicle a company builds that is capable of running on E-85 ethanol, in addition to conventional gasoline, the automaker can increase the number of gas guzzlers it builds. Never mind that fewer than two percent of filling stations sell the corn-based E-85 fuel and that few drivers buy a drop of it.

■An automaker also gets permission to hit lower mileage targets if it improves its cars’ and trucks’ air conditioning systems, making them gentler on the climate. Never mind that the company planned to make the changes even without the credits.

Yes, the rule’s fuel efficiency improvements cut oil use and save money at the pump. They reduce emissions of carbon dioxide, the major cause of global warming. Just look at how the industry did in 2012, the most recent year for which data is available. Despite the loopholes, new cars and light trucks delivered a five percent improvement in mileage — an increase of 1.2 mpg — over the previous year, the EPA reported in December.

But by letting automakers deliver more gas guzzlers, the loopholes create fantasy efficiency. In the long run, they threaten the effectiveness of the mileage-and-emissions program, the biggest single step any nation has taken to fight global warming. The loopholes will result in 38 million tons of extra carbon dioxide pollution being spewed into the atmosphere.

Not for nothing did the auto industry demand these “get-out-of-jail-free” cards before it would accept the standards.

An EPA report issued recently shows that without the credits, Chrysler, GM, Nissan and Ford would have missed the 2012 standard by a wide margin. This is poor payback for taxpayers who gave GM and Chrysler an $85 billion bailout.

The mileage-and-emissions program’s rules allow auto companies to earn credits when their models do better than the plan requires. But the agency also reports that Chrysler and Volkswagen have been turning out gas guzzlers faster than they have been earning credits. They risk violating the standards unless they clean up their vehicles.

The report reveals that in 2012 Honda met both car and truck standards without the loopholes. It was the only major carmaker to do so. If Honda can hit the mark, the others can too.

Automotive engineers have come up with solutions that allow automakers to meet the standards without loopholes. Much of the needed technology is already on Detroit’s shelves: high-strength, lightweight steel or aluminum materials; more efficient transmissions and direct injection engines, for example. The automakers need to get into gear on these gas-saving technologies. And few companies make more than a handful of hybrids or electric vehicles. More need to do so.

All auto companies must deliver cars and trucks that meet the standards without relying on loopholes. That will be good for consumers, who will save money at the pump by buying less gasoline. It will be good for the companies’ bottom line, allowing them to better compete with the leading fuel-efficient nameplates from overseas.

Dan Becker directs the Safe Climate Campaign, which advocates strong measures to fight global warming. James Gerstenzang, the campaign’s editorial director, formerly covered the environment and the White House for the Los Angeles Times.