J.D. Power has named Buick’s dealer service departments the best in the U.S. in its latest Customer Service Index Study, an annual survey that asks consumers what they think of the folks who fix their cars.

Lexus finished first overall, with 874 points of a possible 1,000, leading a trend of higher satisfaction among owners of luxury cars versus those J.D. Power defines as “mass market” brands.

Interestingly, the U.S.-based research firm also names Buick a winner for coming out atop the list of mass-market manufacturers specifically, though we feel they’d fit just fine in the luxury brand category. Nonetheless, Buick’s 860-point result wouldn’t even be good enough for top five in the luxury group, where Lexus was followed by Audi (869), Lincoln (868), Porsche (867), and Cadillac (865).

Nevertheless, Buick ranks first in the mass-market list, trailed by MINI (850), GMC (837), Chevrolet (829), and Nissan (822).

In case you didn’t catch it, General Motors’ service departments appear to have this customer service thing licked: All four of its brands – Buick, Cadillac, Chevrolet and GMC – are in the top five of their respective lists.

At the other end of the spectrum are Fiat Chrysler Automobiles’ (FCA) Fiat (739), Jeep (753), Ram (755), and Dodge (771) brands; FCA avoided a last-place sweep thanks to Mazda (784) placing one spot behind Chrysler (785).

J.D. Power found that dealer service advisors are doing the most to help their stores keep customers happy, with an overall score of 835 for the people doing that job. The highest level of dissatisfaction was with the service facilities themselves, with a score of 794.

A dealer’s use of technology also affects scores, with customers stating they like it when they can schedule service appointments online, and they see their service advisor using a tablet to record information.

A leading cause of customer dissatisfaction is having to take their car back because the first visit didn’t fix the problem that initiated the service process. It’s worth mentioning that 94 percent of those surveyed said their dealership fixed their cars the first time around.

The Customer Service Index Study also proved people still listen to the radio: only 80 percent of those who took their car in to address a radio reception problem left with less static than they arrived with.