Progressive and State Farm, two of America's largest auto insurers, are refusing to write policies in certain cities for some older Hyundai and Kia models that have been deemed too easy to steal, according to the companies.Several reports say the companies have stopped offering insurance on these vehicles in cities that include Denver, Colorado and St. Louis, Missouri. The insurance companies did not tell CNN which cities or states were involved.The Highway Loss Data Institute released insurance claims data last September that confirmed what various social media accounts had been saying: Some 2015 through 2019 Hyundai and Kia models are roughly twice as likely to be stolen as other vehicles of similar age, because many of them lack some of the basic auto theft prevention technology included in most other vehicles in those years, according to the HLDI.Specifically, these SUVs and cars don't have electronic immobilizers, which rely on a computer chip in the car and another in the key that communicate to confirm that the key really belongs to that vehicle. Without the right key, an immobilizer should do just that -- stop the car from moving.Immobilizers were standard equipment on 96% of vehicles sold for the 2015-2019 model years, according to the HLDI, but only 26% of Hyundais and Kias had them at that time. Vehicles that have push-button start systems, rather than relying on metal keys that must be inserted and turned, have immobilizers, but not all models with turn-key ignitions do.Stealing these vehicles became a social media trend in 2021, according to HLDI, as car thieves began posting videos of their thefts and joyrides and even videos explaining how to steal the cars. In Wisconsin, where the crimes first became prevalent, theft claims of Hyundais and Kias spiked to more than 30 times 2019 levels in dollar terms."State Farm has temporarily stopped writing new business in some states for certain model years and trim levels of Hyundai and Kia vehicles because theft losses for these vehicles have increased dramatically," the insurer said in a statement provided to CNN. "This is a serious problem impacting our customers and the entire auto insurance industry."Progressive is also cutting back on insuring these cars in some markets, spokesman Jeff Sibel said in an emailed statement."During the past year we've seen theft rates for certain Hyundai and Kia vehicles more than triple and in some markets these vehicles are almost 20 times more likely to be stolen than other vehicles," he wrote. "Given that we price our policies based on the level of risk they represent, this explosive increase in thefts in many cases makes these vehicles extremely challenging for us to insure. In response, in some geographic areas we have increased our rates and limited our sale of new insurance policies on some of these models."Progressive continues to insure those who already have policies with the company, he said. Progressive is also providing them with advice on how to protect their vehicles from theft.Michael Barry, a spokesman for the Insurance Information Institute, said it was very unusual for auto insurers to simply stop writing new policies on a given make or model of vehicle."They generally want to expand their market share depending on where they're doing business," he said.Hyundai and Kia operate as separate companies in the United States, but Hyundai Motor Group owns a large stake in Kia and various Hyundai and Kia models share much of their engineering.Engine immobilizers are now standard on all Kia vehicles, according to a statement by the automaker and the company says it has been developing and testing security software for vehicles not originally equipped with an immobilize. Kia said it has begun notifying owners of the availability of this software, which is being provided at no charge.Hyundai said it is providing free steering wheel locks to some police departments around the country to give local residents who have easily stolen Hyundai models. Hyundai dealers are also installing free security kits for the vehicles, the company said.