The quality of American cars has dropped for the first time in 15 years, and the problems are serious. This isn't your casual radio mishap.

J.D. Power and Associates released their annual dependability survey Wedensday morning, in which they query owners of three-year old cars — models built in 2011 — about problems they have suffered since purchase. For the first time since 1998, the survey has reported 133 problems per 100 vehicles. That's a six percent increase over last year's results.  

The problem, it seems, was changes made to improve fuel economy. "Until this year, we have seen a continual improvement in vehicle dependability," David Sargent, vice president of global automotive at J.D. Power, explains in the press release. "However, some of the changes that automakers implemented for the 2011 model year have led to a noticeable increase in problems reported." The Seattle Times explains

Automakers are rapidly implementing new engine technology to save fuel, including direct fuel injection and turbocharging, stop-start systems that automatically shut cars down at traffic lights and transmissions with higher gears. 

Sargent says the new, more complex systems are resulting in recurring problems like engine hesitation, rough transmission shifts, and a lack of power. 

Usually problems in three year old models are limited to the electronics, or the radio — trivial issues that are easily repaired. But these are major design issues, and not so easy to fix, which means the trend could continue next year. That's not good for the automotive industry's long-term recovery. 

Meanwhile, J.D. Power found five most reliable brands are: 

  1. Lexus
  2. Mercedes-Benz
  3. Cadillac
  4. Acura
  5. Buick