This is Consumer Reports, not JD Power, and they said they surveyed for issues in the first 12 months. It's about "new" cars after all so you can't go further back than that. They also weigh issues for their severity. Where are you seeing that their methodology is the same as JD Power?
> Every year CR asks its members about problems they’ve had with their vehicles in the previous 12 months. This year we gathered data on over 330,000 vehicles, from the 2000 to 2023 model years, with a few early-introduced 2024 model years.
> We study 20 trouble areas, from nuisances—such as squeaky brakes and broken interior trim—to major bummers, such as potentially expensive out-of-warranty engine, transmission, EV battery, and EV charging problems. We use that information to give reliability ratings for every major mainstream model.
> We weigh the severity of each type of problem to create a predicted reliability score for each vehicle, from 1 to 100. We use that information to give reliability ratings for every major mainstream vehicle. (The reliability rating is then combined with data collected from our track testing, as well as our owner satisfaction survey results and safety data, to calculate each test vehicle’s Overall Score.)
https://www.consumerreports.org/cars/car-reliability-owner-s...
> Every year CR asks its members about problems they’ve had with their vehicles in the previous 12 months. This year we gathered data on over 330,000 vehicles, from the 2000 to 2023 model years, with a few early-introduced 2024 model years.
> We study 20 trouble areas, from nuisances—such as squeaky brakes and broken interior trim—to major bummers, such as potentially expensive out-of-warranty engine, transmission, EV battery, and EV charging problems. We use that information to give reliability ratings for every major mainstream model.
> We weigh the severity of each type of problem to create a predicted reliability score for each vehicle, from 1 to 100. We use that information to give reliability ratings for every major mainstream vehicle. (The reliability rating is then combined with data collected from our track testing, as well as our owner satisfaction survey results and safety data, to calculate each test vehicle’s Overall Score.)