JD Power is akin to paid studies like an IDC "Study", or Gartner and Forrester "research". Or even better - Tolly "reports". And finally the complete sham that is NSS Labs. They're all pay for play - and using NSS as an example, they get paid on both sides. First the vendors pay the "lab fee" (source: I worked for a large security vendor and was involved in this process) to be included and for any reruns of the test if you don't like the results. The other half of it is charging customers for the "unbiased" reporting / research. It's a racket. Someone sent me a link to this JD report last month and I just responded with a rolling eye emoji. JD Power has declared GM/Chevy the winner for their entire existence if you watch any of their commercials. Clearly it works to an extent. And their loyal buying base oft references the "quality" represented from personal experience.
However, starting that conversation about the JD link got me looking. I started comparing reliability of Tesla to all other luxury brands in my subscription to Consumer Reports (they, at least, they buy what they test and have no brand influence or conflicting interest). While the Model X seems to fare the worst the Model S doesn't rank lower than comparable BMW, Mercedes, Audi, etc for the most part. In a lot of those direct comparisons Tesla has higher reliability, but still relatively poor given the cost of the product.
I fully agree with the parent comment here. Tesla likely told JD to go fly a kite and JD's enterprising sales folks went to Detroit and conjured up a nice fluff piece. Or, maybe this is a sign of Detroit starting sling mud because, too little too late. From my perspective I hope Detroit gets their act together quicker than they have been as I'd like more choice for EV. I don't own any Tesla products, but I likely will in the next 3-5 years if the current landscape of EV options doesn't significantly change. I like the idea of a lot of the concepts Tesla has brought to market, but as a consumer I don't really care what badge is on the vehicle anymore. It's unfortunate those who are competing are often lacking in many ways when compared to the current market leader.