WASHINGTON (Reuters) - A U.S. Senate panel on Tuesday will ask automakers and regulators why tens of millions of vehicles with faulty Takata air bag inflators remain on the road years after deaths prompted the largest auto safety recall in history.

FILE PHOTO - A logo of Takata Corp is seen with its display as people are reflected in a window at a showroom for vehicles in Tokyo, November 6, 2015. REUTERS/Toru Hanai/File Photo

Nearly 30 million vehicles remain unrepaired in the recall impacting 19 automakers. At least 22 deaths and hundreds of injuries worldwide are linked to Takata inflators that can explode, unleashing metal shrapnel inside cars and trucks. The defect led Takata to file for bankruptcy protection in June.

The recall process “may play out for another 10 to 15 years,” Senator Jerry Moran, who heads the Senate Commerce Committee panel that deals with consumer protection and other issues, said in his written opening statement for the hearing.

“It is imperative that all these recalled vehicles are repaired,” Moran said.

Heidi King, the National Highway Traffic Safety Administration’s deputy administrator, said in written testimony that 21 million of the 50 million air bag inflators recalled by 19 automakers have been repaired to date.

At least 10 million more inflators are expected to be recalled over the next few years, including some interim replacement inflators, NHTSA has said. “Progress is uneven and overall completion rates are not where we want them to be,” King said.

Senator Bill Nelson of Florida, where many of the deaths occurred, criticized NHTSA for not pushing automakers harder. The senior Democrat on the Senate Commerce Committee, Nelson said in his written statement there is a wide disparity in recall completion rates.

The agency “still seems to be playing a game of regulatory whack-a-mole and twiddling its thumbs when it comes to actually enforcing the coordinated recall approach and benchmarks for automakers,” Nelson said.

In February, Ford Motor Co F.N warned an additional 33,000 owners of older pickup trucks to stop driving them until Takata inflators can be replaced after the report of a second death in a 2006 Ford Ranger caused by a defective Takata inflator. Ford is testifying Tuesday.

The other 20 deaths have occurred in Honda Motor Co 7267.T vehicles.

Rick Schostek, executive vice president of Honda North America, will tell the panel the company has repaired 72 percent of the 18.5 million inflators recalled to date. “This is far ahead of the rest of the industry and reflects our extraordinary effort to reach out to customers,” he said in testimony.

Under the bankruptcy plan, Takata is selling most assets to Key Safety Systems, a unit of China’s Ningbo Joyson Electric Corp 600699.SS.

Testimony from Key Safety Chief Financial Officer Joseph Perkins says the company hopes to win approvals so it can close the deal in April 2018.

John D. Buretta, the independent monitor overseeing the massive recalls, said in written testimony that nearly 75 percent of the recalled vehicles are more than 10 years old.

Previously, Buretta said many automakers “were slow to engage meaningfully and think strategically about how to maximize recall repairs and to deploy the kind of innovative recall techniques needed for the Takata recalls. More recently, there has been marked improvement.”

Takata pleaded guilty in 2017 single felony count of wire fraud to resolve a U.S. Justice Department investigation and agreed to a $1 billion settlement.