As automakers ratchet down the fuel consumption of their cars to meet tougher federal standards, the top Japanese automakers already have an enormous head start from credits they earned since the 2009 model year.
Because they outperformed old fuel economy standards before new requirements were phased in, Toyota, Honda and Nissan have a huge cushion that will help them meet increasingly tight standards.
Last month the EPA quietly posted a report that shows these three companies have so many credits that their current fleets, unchanged, could meet EPA requirements through the 2016 model year, said David Friedman, a senior engineer at the Union of Concerned Scientists.
The companies are highly unlikely to do that, Friedman said, because they need to meet much stricter standards from 2017 to 2025 and because fuel economy has become a crucial selling point.
But these companies still have enough credits "that they could slow down near-term investments in clean cars," he said.
When the new standards started to phase in for the 2012 model year, Toyota held 86 million EPA credits. Each credit represents one more metric ton of carbon dioxide that its vehicles could emit over their lifetimes than the Obama administration's new program nominally allows.
The credits give Toyota more options for meeting new EPA limits on tailpipe emissions, which will get 3 to 5 percent stricter each year in tandem with new corporate average fuel economy standards that ramp up to a nominal 54.5 mpg in the 2025 model year.
Toyota, the dominant player in hybrids, and other automakers have kept mum on plans for these credits, which can be used until the 2021 model year, except for the credits from 2009, which last only five years.
Tom Stricker, vice president of technical and regulatory affairs at Toyota Motor North America, acknowledged that the credits are a "valuable tool for future compliance."
Automakers may sell their excess credits to competitors that fall short. And while there are some limitations on using credits to build gas-guzzlers, automakers with credits would have more leeway to build more powerful vehicles with lower mpg than competitors that are feeling the crunch of CAFE.
"It will give a company like Toyota an opportunity to promote performance a little more aggressively than we will be able to," said an executive who plans CAFE compliance for another major automaker. "They will have the ability to not ratchet down the performance of their mainstream products as much. Do we wish we had more? Yes. Do we wish they had less? Sure."