For me it was when i bought a VW tiguan almost 10 yrs ago. Biggest financial blunder of my life!!
A year after using it, the transmission fails on me and I had to spend an arm and a leg getting it sorted. After that, I wanted to sell it but i barely got any buyers and after almost 6 months, i let it go for a throw away price. I mean no offense to any one, as everyone has their own opinions, but after that, I personally decided to never ever go for European cars ever again. I swear by Japanese makes as I feel they stand the test of time and yet they are not as expensive to maintain(or buy) as their European counterparts. Sure their cars are not as teched out as say - german makes for example but I would rather drive a no-frills noisy truck that will last longer than a fancy european car with numerous sensors, features and what not, which probably wont last very long.