Deployed Takata air bags are seen on the driver and passenger sides of a 2007 Dodge Charger at a recycled auto parts lot in Detroit, May 20, 2015. The National Highway Traffic Safety Administration has yet to take over the handling of the largest auto safety recall in history. Reuters/Rebecca Cook

Automakers are getting a failing grade for their record on replacing flawed air bag inflators in millions of cars on U.S. roads, and the federal auto safety watchdog is debating whether to invoke its power to help speed up the process. The National Highway Traffic Safety Administration announced at a public meeting in Washington Thursday that it would decide by Thanksgiving if it will flex its regulatory muscle in the largest auto safety recall in U.S. history.

The air bag inflators, made by Japanese auto parts supplier Takata Corp., can explode when they’re deployed, spewing fragments into the bodies of drivers and passengers. The deadly flaw has been linked to at least eight deaths and about 100 injuries worldwide. (The number could be higher since the causes of death and injury could be misdiagnosed at accident scenes.) At least 11 automakers and dozens of models dating back more than a decade are covered by the recall in the U.S. Millions more are affected worldwide.

More than two years after automakers began telling customers to bring their cars in for repair, the NHTSA still hasn’t invoked a little-known power it has to accelerate remedies in product safety recalls. Administrator Mark Rosekind said in a presentation Thursday that only 4.4 million of 23.4 million air bag inflators in the U.S. have been replaced, or about 18 percent. At least 19.2 million vehicles on U.S. roads have one or two flawed inflators, which means most cars are still carrying safety parts that behave like fragmentation grenades.

The power, known informally as the accelerated remedy provision, allows the NHTSA to take over when it feels manufacturers are taking too long to fix dangerous flaws. In May, the NHTSA announced it would consider implementing its power. But on Thursday, Rosekind said his agency was still mulling the move.

“It allows them to do certain things, like force manufacturers to use one or more suppliers to speed up the process,” said Michael Brooks, staff attorney at the Center for Auto Safety. “It’s something that’s rarely done, but NHTSA could step in and do that.”

Part of the agency’s hesitancy could be that there’s little it can really do except confirm what manufacturers are already saying: that they’re fixing the cars as quickly as the supply of air bag parts are available.

“It’s like filling a tub with the drain open,” Honda USA spokesman Chris Martin told International Business Times in May. “We’re refilling the tub constantly.”

The NHTSA said Takata is making 2.8 million units in October using parts supplied by air-bag makers Autoliv Inc., Daicel Corp. and TRW Automotive Inc.

But if the agency takes over, it could consolidate and streamline efforts, as well as ensure that manufacturers are doing everything possible to repair cars as quickly as possible.

The air bag inflators contain ammonium nitrate, a common ingredient used in controlled explosions, such as building demolitions. The compound’s reaction with water – and humidity – is believed to be the cause of the problem. Over time, the chemical can change to explode with more force than needed to rapidly inflate the air bag. Takata has said vehicles bought or registered in humid states like Florida and Louisiana are at greater risk.

If the NHTSA decides to initiate control over the recall, which involves at least a dozen companies (Takata and the 11 involved automakers), it could, among other things, allow independent car repair shops, not just manufacturers, to make the fix when the parts become available, order Takata and automakers to perform additional tests on replacement parts and expand the air bag recall to include more cars in the future without waiting for automakers to make those decisions.

The following is a list of affected cars in the U.S. compiled by the NHTSA. The list was last updated on Sept. 16, 2015. U.S. vehicle owners can also plug their Vehicle Identification Number into the NHTSA recall database to check on this and other recalls. In April, Cars.com discovered that NHTSA’s recall website was incomplete, so owners should also check with their automaker’s online recall tools. Click on the links below to go to those sites for U.S.-specific recalls.

2000 - 328i
2001-2006 - M3
2002-2003 - M5
2000 - 323i
2002-2006 - 325Ci
2002-2006 - 330Ci
2002-2003 - 325iT
2002-2003 - 325XiT
2001-2006 - 325i
2001-2005 - 325Xi
2001-2006 - 330i
2001-2005 - 330Xi
2002-2003 - 525i
2002-2003 - 530i
2002-2003 - 540i
2003-2004 - X5 3.0i
2003-2004 - X5 4.4i

Fiat Chrysler Automobiles:
2007-2008 Chrysler Aspen
2005-2010 Chrysler 300
2005-2010 Chrysler 300C
2005-2010 Chrysler SRT8
2008-2010 Dodge Challenger
2005-2010 Dodge Charger
2005-2011 Dodge Dakota
2004-2008 Dodge Durango
2005-2010 Dodge Magnum
2003-2008 Dodge Ram 1500
2003-2009 Dodge Ram 2500
2003-2009 Dodge Ram 3500
2008-2010 Dodge Ram 4500
2008-2010 Dodge Ram 5500

Ford Motor:
2004-2006 Ranger
2005-2006 GT
2005-2014 Mustang

General Motors:
2007-2008 Chevrolet Silverado 2500
2007-2008 Chevrolet Silverado 3500
2007-2008 GMC Sierra 2500
2007-2008 GMC Sierra 3500
2003-2007 Pontiac Vibe
2005 Saab 9-2x

2001-2007 Accord
2001-2005 Civic
2003-2005 Civic Hybrid
2002-2006 CR-V
2003-2011 Element
2002-2004 Odyssey
2003-2008 Pilot
2006 Ridgeline
2003 Acura CL
2002-2003 Acura TL
2003-2006 Acura MDX
2005 Acura RL

2004-2006 B-Series Truck
2003-2008 Mazda6
2006-2007 Mazda Mazdaspeed6
2004-2005 MPV
2004-2008 RX-8

2004-2006 Lancer
2004-2006 Lancer Evolution
2004 Lancer Sportback
2006-2009 Mitsubishi Raider

2001-2003 Nissan Maxima
2002-2006 Nissan Sentra
2002-2004 Nissan Pathfinder
2001 Infiniti I30
2003-2005 Infiniti FX35
2003-2005 Infiniti FX45
2002-2004 Infiniti I35
2006 Infiniti M35
2006 Infiniti M45
2002-2003 Infiniti QX4

2003-2005 Baja
2004-2005 Impreza
2003-2005 Legacy
2003-2005 Outback

2003-2007 Corolla
2003-2007 Corolla Matrix
2004-2005 Rav4
2002-2007 Sequoia
2003-2006 Tundra
2002-2007 Lexus SC

Daimler Trucks North America:
2008-2009 Sterling Bullet 4500
2008-2009 Sterling Bullet 5500

Daimler Vans USA LLC:
2006-2008 Dodge Sprinter 2500
2006-2008 Dodge Sprinter 3500
2007-2008 Freightliner Sprinter 2500
2007-2008 Freightliner Sprinter 3500