Porsche slipped to second after holding the title for three years in the market research firm's Initial Quality Study, released today.
Ford improved to 102 reported problems per 100 vehicles and Chevrolet to 103, just behind Toyota's sixth place score of 101.
That put the three top-selling brands in the United States in the same league when it comes to complaints during the first 90 days of ownership.
"There is no statistical difference between a 101 and a 102 or, for that matter, between a 101 and a 103," said David Sargent, JD Power's vice president of automotive research, in a presentation to the Automotive Press Association.
Overall industry quality improved to its best level in the study's 23 years, and domestic brands continued to close the gap between their performance and the industry average.
That average was 108 reported problems per 100 vehicles, down from 118 in 2008. Owners of US domestic brands recorded an average of 112 problems per 100 vehicles.
A year earlier, the US domestics had 124 reported problems, or six more than the average.