From Doug Short:
One interpretation of this graph might be that people can’t afford to replace their cars as often. To me, it says that cars are made much better than they used to be. It used to cost more to maintain and repair an older car with more miles than it did to just buy a new one. Today I drive an 8 year old car with 160,000 miles on it. I would never have considered doing that 20 years ago, because I would have been afraid to be stranded in a broken down car with my kids. Today, I’m not worried about it breaking down.
This graph is referenced in the above article but not shown. I think this is more a reflection (in the long term) of demographic changes than economic struggles: