Automakers also likely will install devices to capture heat wasted in the exhaust system, Patel said. By recovering waste heat, engineers can quickly warm fluids in, say, the transmission, which reduces friction.
Tier 3 emissions standards phase in gradually from 2017 to 2025 and vary by vehicle class. In 2017, new light vehicles sold by automakers cannot exceed a fleet average of 86 milligrams of smog-forming emissions per mile.
Those limits decrease 7 mg per mile every year through 2025, when fleetwide emissions must average 30 mg per mile.
Starting in 2017, the nation's refiners must reduce sulfur from 30 parts per million to the Tier 3-mandated 10 ppm in 2025. That low-sulfur fuel is key to reducing tailpipe emissions. Low-sulfur fuel increases the effectiveness of existing emissions systems and opens the door to new technologies.
The regulations should pose few technical problems for automakers in the first few years, says Tenneco's Jackson. Tenneco is a major supplier of catalytic converters and emissions equipment.
"The manufacturers already know what they are going to do for 2017, 2018 and 2019. What we are working on are the solutions for 2020 and beyond," Jackson said. "Remember, that it is a declining scale. For the next five years the manufacturers are very confident in their strategies."
Oliver Schmidt, head of the Volkswagen Group of America's Energy and Environmental Office, says VW's lineup of gasoline-powered vehicles can already comply with the Tier 3 rules starting in 2017, except for one or two models that are "pretty old technologywise" and will be phased out by 2019 and for which the company is working on interim compliance solutions.
But the Tier 3 emissions standards pose a larger challenge for VW's diesel-powered vehicles. Schmidt says VW is investigating new exhaust aftertreatment systems that will heat up faster than those now used for more effective emissions reduction. But doing so would come at the expense of fuel economy, Schmidt said, and fuel economy requirements are growing ever tougher.
"On the one side, I have to save fuel and on the other side I want to heat up my aftertreatment system as fast as possible," he said. "This is an issue that we are facing there, and we are working on new technologies."
One technology VW is investigating would create a secondary exhaust burn after initial fuel combustion to reduce emissions, Schmidt said.
Volkswagen sells more diesels in the United States than any other automaker.
Other automakers also are putting their plans in place to meet Tier 3.
Toyota plans to meet the standards by offering a gasoline-electric hybrid powertrain across nearly its entire lineup, said Susan Collet, senior principal engineer for vehicle regulations.
GM spokesman Tom Read said his company's emissions engineers are developing proprietary technologies that improve the performance of catalytic converters and evaporative systems, which prevent gasoline vapors from escaping into the atmosphere.
Costs likely will increase because more onboard diagnostic equipment will be needed to monitor the emissions system.