Detroit - Toyota's top engineer said on Monday that diesel-powered vehicles that would clear strict clean-air regulations in the United States would be too pricey to be worth the fuel savings.
"I won't deny that we won't be offering a diesel in the United States some time in the future," said Executive Vice President Masatami Takimoto, who overseas Toyota's research and development.
"But right now we think hybrids are much more cost competitive," he told reporters on the sidelines at the North American International Auto Show in Detroit.
Domestic Japanese rivals Honda and Nissan have both said they were preparing a clean diesel powertrain for launch by the end of the decade in the United States, which is due to introduce the strictest diesel emissions regulations in the world soon.
But with the particulate filter traps and other added components needed to clean tailpipe emissions, Takimoto said the likely price premium on the cars would not justify a choice over hybrids for now, at least in the United States.
Toyota, a relative laggard in diesel technology, in November tied up with diesel-savvy Japanese truck maker Isuzu in an attempt to catch up, but Takimoto said a roadmap on how to proceed was wide open.
Plug-in hybrids, which were all the buzz at the auto show in Detroit this week, could be a good way to save fuel and cut carbon dioxide emissions, Takimoto said.
But he also stressed that an advanced enough battery was still years away from practical application.
"To make plug-in hybrids feasible, you'd need a battery that is far smaller, lighter and advanced than the best lithium-ion batteries out there today," he told reporters.
He said Toyota was currently developing such a battery in-house, as well as with battery-business partner Matsushita Electric Industrial.
Takimoto said the best use of plug-in hybrids also depended heavily on the method in which countries produce electricity. If fossil fuels such as coal are used to create electricity, the resulting emissions on a "well-to-wheel" basis would remain high, he noted.