The trend toward downsized turbocharged engines has in part led to a 6% year-over-year increase in problems reported by owners of 3-year-old vehicles, according to the J.D. Power Vehicle Dependability Study.

The study, which examines problems reported during the past 12 months by 41,000 original owners of ’11-model vehicles, finds overall vehicle dependability averages 133 problems per 100 vehicles, an increase from 126 PP100 in 2013. The results mark the first time since 1998 the average number of problems has increased.

“Until this year, we have seen a continual improvement in vehicle dependability,” David Sargent, vice president-global automotive, says in a statement. “However, some of the changes that automakers implemented in 2011 have led to a noticeable increase in problems reported.”

Engine and transmission issues increased by nearly 6 PP100, accounting for most of the overall 7 PP100 uptick in reported problems. The decline in quality was more acute for vehicles with 4-cyl. engines, where complaints increased nearly 10 PP100, according to the study.

Smaller engines, as well as large diesel engines, tend to be more problematic than 5- and 6-cyl. mills, according to J.D. Power.

“Automakers are continually looking for ways to improve fuel economy, which is a primary purchase motivator for many consumers, particularly those buying smaller vehicles,” Sargent says. “However, while striving to reduce fuel consumption, automakers must be careful not to compromise quality. Increases in such problems as engine hesitation, rough transmission shifts and lack of power indicate that this is a continuing challenge.”

Among individual nameplates, Lexus took the top spot for the third consecutive year, with the brand averaging 68 PP100. Mercedes was the runner-up with 104 PP100, followed by Cadillac (107), Acura (109) and Buick (112).

The industry average is 133 PP100, and a number of well-known brands placed below that level, including Ford with 140 PP100, Nissan (142), Audi (151), Chrysler (155), Volkswagen (158) and Hyundai (169). BMW’s Mini brand placed dead last with a 185 PP100 ranking.

One model from each vehicle segment received an award for having the fewest problems reported. The Honda Fit took the subcompact-car category, while the Toyota Camry placed best in the Midsize Car segment.

The top light-duty pickup was the GMC Sierra, while the Honda CR-V was the highest-ranked vehicle in the Compact CUV segment.

General Motors received eight segment awards, more than any other automaker in 2014, for the Buick Lucerne, Cadillac DTS, Cadillac Escalade, Chevrolet Camaro, Chevrolet Volt, GMC Sierra and GMC Yukon.

The study is watched closely by automakers as well as consumers. According to J.D. Power, 56% of owners who reported no problems stayed with the same brand when they purchased their next vehicle. Brand loyalty slipped to just 42% among owners who reported three or more problems.

Further, 23% of consumers avoided brands that ranked in the lowest quartile of the study because of reliability concerns. In contrast, only 9% of consumers cited the same reasons for avoiding brands that ranked in the top fourth.

“By combining our customer research with trade-in data, we see a very strong correlation between dependability and real-world brand loyalty,” Sargent says. “Also, we see that brands with lower dependability are likely to be shut out of a significant piece of the market, as many consumers will not even consider purchasing one of their vehicles because of concerns about its likely reliability.”

bpope@wardsauto.com