A rash of Hyundai and Kia thefts in the past couple of years has dropped sharply after the South Korean automakers made antitheft software updates to vulnerable models.

The nonprofit Insurance Institute for Highway Safety said the updates, which started last year, have reduced the rate of theft among the vehicles by more than half.

“The companies’ solution is extremely effective,” said Matt Moore, senior vice president of the institute’s sister group, the Highway Loss Data Institute. “If you own a Hyundai or Kia vehicle without an electronic immobilizer, you should call your local dealer about getting the software upgrade today.”

The updates started in February 2023 after thieves targeted models without electronic mobilizers, even posting social media videos to instruct others in their theft methods. IIHS said the software updates allow the vehicles to be started only with the owner’s key or an identical duplicate used in the ignition.

Updated vehicles also get a window sticker indicating the antitheft capability in order to deter prospective thieves.

Hyundais and Kias model years 2011 to 2022 didn’t come with electronic immobilizers as standard, or what IIHS said is about two dozen models.

As of last December, about 30% of eligible vehicles had gotten the software update, and their theft claim frequency has since been 53% below those that hadn’t gotten the upgrade, IIHS said. The claims also cover damage to stolen vehicles, items inside the vehicles that were stolen, and vehicle parts thefts.

The automakers’ theft rates should eventually return to industry normals as criminals become aware many are no longer easy targets “and the fad gets stale,” Moore said.

Hyundai and Kia settled a class-action lawsuit over the thefts in the spring of last year in the amount of $200 million, covering about nine million vehicle owners between them.

In addition to the software upgrade, the companies reimbursed owners for steering wheel locks and worked with AAA to insure effected vehicles. But many major U.S. cities sued them over the thefts, which sometimes ended with episodes of dangerous driving, including collisions, and many attorneys general urged them to do more about the problem, including a recall. Some insurance companies sued them. Part of the models prone to theft weren't eligible for the software update.