The study, which polls owners to measure vehicle servicing quality, vehicle pick-up, service advisor, service initiation, and service facility, is now into its seventh year.
The 2016 index is based on the responses of 4666 owners who purchased between August 2011 and September 2016, and had their vehicle cared for at an authorised dealership service centre between August last year and September this year.
Among 'mass market' brands, Mazda topped this year's index, with a score of 834 on a 1000-point scale, reclaiming the crown that Honda stole back last year - having last held it in 2012, tying for top spot with Toyota.
Responding to the results today, Honda Australia chief Stephen Collins conceded that the Honda brand has seen "considerable variability" in the JD Power CSI rankings.
"For example, in 2014 Honda ranked seventh, in 2015 it was number one and in 2016 it ranks sixth. Honda does not subscribe to the JD Power survey and as such we don’t know why such variability exists. However, as a business we're keen to understand it and are investigating," Collins said.
"Honda takes customer satisfaction extremely seriously and measures this on an ongoing basis. We subscribe to several syndicated surveys that measure customer satisfaction in sales and service and the company consistently ranks in the top three makes.
"Honda takes customer service seriously and the company strives to provide the highest levels of service with a high degree of cooperation with our 107 Dealers nationally."
Hyundai follows its sister brand in a tight race, on 807, while Honda finished on a score of 806.
While Honda's fall may come as a shock to the brand, staff and dealers for the Holden brand are likely celebrating, with the lion brand jumping ahead of Volkswagen, Nissan, Mitsubishi and Ford since last year's survey. The leap will be a relief, after having fallen from a fourth-place 2014 finish.
Little else has changed about the bottom order, however, with most scores improving but not significantly enough to move many others up the ladder.
Loi Truong, JD Power's senior country manager for Australia, said: “Delighting customers translates to higher loyalty and advocacy.” A message that must seem lost on some brands.
The data shows that 75 per cent of satisfied customers "definitely will" recommend the brand to family and friends, and 84 per cent said the same of the likelihood they'll return to the same dealer for paid service work.
Of dissatisfied customers, only 30 per cent said they "definitely will" recommend the brand, and only 13 per cent will return to the same dealer for servicing.
Customers who received a notification of upcoming servicing needs were found to be more satisfied (62 per cent), as were those who received a detailed cost estimate before service is performed (68 per cent).
“Aftersales service contributes significantly to a dealer’s overall profitability,” said Mohit Arora, executive director at JD Power.
“Customer retention is a vital aspect of a dealer’s business that not only allows them to grow their business but also builds long-term customer relationships.
"Offering service packages and capped price servicing options entice customers to visit the dealership for their regular servicing needs, but it needs to be complemented with a proficient, convenient and an engaging customer experience.”