Of new car buyers from the auto companies and then use standard sampling phone surveys.

An interesting thing I found d doing this was finding a related article on the same topic conducted by Consumer’s Reports. Their list varies wildly. For instance, the top brand in their survey was Mazda, and Mazda was in the middle of the JD Powers survey. Kia took a big dive in CR’s study but moved up in JDP.

The reasons are likely sampling and differences in what is measured and how it’s weighted. For instance, CR is a survey of subscribers and IIRC consumers can I initiate participation. The CR article specifies what they compile, and I don’t recall all of that but it goes way beyond number of issues with the vehicle.