I was surprised to come across the link below last week. While it is in French, the graphs are readable in all languages. The curves represent the number of breakdowns per 1000 vehicles per year. A breakdown means the TCS had to be called out. (The TCS is the Swiss equivalent of the AAA or AA.) While the data ends in 1999, the message is clear - over the period represented, breakdowns increased by 20% on average across all makes.
The upper graph is for makes with above average breakdown rates, and the lower one for the below-average (better) breakdown rates. The most spectacular decline is by Opel. Mercedes was the most reliable make in 1986, but has declined significantly since then, remaining better than average.
http://www.tcs.ch/tcs.html?/webtcs/TCSPubli.nsf/(DocByID)/(BE9473ADD4D4B0A4C12569DC0057781B)!OpenDocument&language=fr