(AP Photo/David Goldman)

It's the worst year for auto recalls in U.S. history, with more than one in five cars and trucks at risk of sometimes critical, deadly defects. But the disjointed recall system patched together by automakers and regulators is leaving millions of broken vehicles still on the road.

Federal regulators on Wednesday urged the owners of 7.8 million Hondas, Toyotas, BMWs and other vehicles to “take immediate action” on a recall for malfunctioning airbags that blast out metal shards. The defect, tied to Japanese auto parts manufacturer Takata, has been linked to at least two deaths and dozens of injuries.

Those faulty cars and trucks have joined 50 million others recalled nationwide so far this year, more than three times as many vehicles sold across the country in 2013. But car companies say there's a short supply of parts used to fix those defects, and safety regulators can't even agree on how many vehicles have the dangerous flaws.

After landmark cases against General Motors and Toyota, automakers are running scared, and some are sounding the alarm over problems that may have once gone ignored. Safety advocates said that is laying bare the fundamental weaknesses of the broken recall system: neglected warnings, crucial delays and confusing messages that leave even attentive drivers at risk.

John Kauffman Jr., 34, said he was driving on the interstate near Hagerstown, Md., at dusk on Saturday when his 2011 Chrysler 300 lost all power and began filling up with smoke. To stop, he had to wrestle the car across several lanes of heavy traffic, all while struggling to breathe.

On Monday, having read about a Chrysler recall connected to faulty alternators, Kauffman called the dealership, which told him to tow his car in. But after replacing the part, dealer technicians told him the recall was not yet official, and that he would have to pay the full $1,041 for the repair.

Chrysler spokesman Eric Mayne said that while the company had announced the recall of 470,000 cars and SUVs, the recall had not been officially launched and Chrysler would not begin notifying drivers until next month. The spokesman declined to speak directly to Kauffman's case but said the company would reimburse owners who paid for repairs later blamed in a recall.

"If they know there's a possibility a car can shut down on the interstate, what are they waiting for? A fatality?," Kauffman said. “I told them, ‘What if I couldn’t get the car off the road? Do you care about that?’ And their main thing was: ‘Sorry for the inconvenience.’ And I wanted to say, ‘Death is not an inconvenience.’”

Why are so many recalls happening now? Advocates say the auto industry was spooked in March when federal prosecutors announced a $1.2 billion fine against Toyota, the largest criminal penalty for an automaker in the United States, over missteps in Toyota's recall of 10 million cars.

Major automakers are recalling millions of vehicles due to potentially defective front passenger air-bag inflators that can rupture and spray metal shrapnel. (Reuters)

That has come alongside the even bigger recall of General Motors. The carmaker waited years to order recalls for millions of cars with faulty ignition switches, which in slipping out of place could disable air bags and cause the cars to stall. That defect is now tied to 29 deaths, 27 injuries and potentially hundreds more, according to data released last week from an attorney hired by GM to compensate victims.

Federal prosecutors could launch a new investigation into Takata, the Wall Street Journal reported late Wednesday. A spokesperson for the U.S. Attorney’s Office in New York would not confirm the report.

But launching the recall is just the start. Drivers often find a whole series of hurdles that can block them from getting their car's defects fixed.

Nearly one-third of recall notices mailed to vehicle owners are ignored, according to the National Highway Traffic Safety Administration, and automakers have been criticized for obscuring how severe the problems can be. "The letter that goes to the consumer is the most critical factor in getting a higher level of response," said Joan Claybrook, the former NHTSA head and longtime traffic safety advocate. But "a lot of times it's pablum. The auto companies dumb it down so it doesn't say, 'Alert, alert, you could die.'"

Those defective cars can then spread widely to used car lots and the driveways of unsuspecting buyers. About 3.5 million recalled cars and trucks were listed for sale last year, according to Carfax.

Keeping track of what cars are problematic can also prove a hassle: Stericycle, a recall consultant and service firm for automakers, said there have been 544 separate recalls announced this year, or nearly two recalls a day.

"We’re living in what we’re now referring to as the year of the automotive recall, and unfortunately the population of drivers may become numb to that," said Mike Rozembajgier, a vice president of Stericycle. "There's automotive recall fatigue. People begin to think, 'I already checked,' or 'That's not my car,' or 'That's not that serious.' But they're all serious. They all have safety implications."

When buyers do respond, they may find that the dealers don't have parts ready for repairs. Honda said it lacks the parts to promptly fix its more than 5 million Accords, Civics, Odysseys and other cars it said this week were at risk of lethal airbags.

And the temporary fixes dealers might make before the needed parts come in can often seem woefully lacking, advocates said. Toyota dealerships will disable air bags and attach notes on the glove box warning against riding in the passenger seat. Chrysler told owners of its Jeep SUVs this month that, while waiting for ignition-switch repairs, they should pull their knees back and “remove all items from their key ring.”

The mess of confusing, contradictory information can often cause car owners to give up and ignore the problem.

"There is a frustration factor. ... If parts are not immediately available, people will say, 'If it were that serious, they'd tell me to park it,'" said Clarence Ditlow, an executive director for the Center for Auto Safety, a consumer group. "And that's why it's so important to get the initial stage of the recall right. Once you miss the initial opportunity, you're going to lose people."

A few simple solutions, advocates said, could help boost driver awareness and recall participation. States could require vehicle recall checks whenever a driver wants to renew a driver's license. And car companies in the past have offered to pay dealerships who find drivers needing a recall or repairs.

But lawmakers and automakers have stumbled in even preventing relatively obvious recall problems. Even today, for example, used-car dealers and rental car companies can still stock vehicles with recall-worthy defects. (That could potentially change.)

Federal regulators may be part of the problem. The NHTSA has been skewered for failing to act on the fatal flaw in GM’s ignition switches when the agency knew about it, as early as 2007. Regulators have pointed back at GM, saying the automaker “hindered NHTSA’s efforts every step of the way.”

But regulators have struggled with even the basic elements of a recall. The Takata recall list that safety regulators shared on Monday was drastically incomplete: The number of defective vehicles has grown by more than 3 million in the days since, and some cars initially recalled weren't defective, after all.

Government Web sites with information on the recalls, including a search site drivers could use to look up whether their vehicle had problems (www.safercar.gov/vinlookup), were down all Tuesday, in the hours after news of the massive airbag recall had spread, and remained down Wednesday morning.

"If the government agency is confused," Ditlow said, "how can you not be confused?"