would be interesting to see vehicle age by geography. I suspect all the rural farmers are the ones skewing the average (it's not unusual to have a 20-30yr old truck out on the farm.. You can fix them with the same tools as your tractors).
And 6.6 years in Japan, in 2011: http://blogs.wsj.com/drivers-seat/2011/12/02/are-cars-losing... Americans do a lot of silly things but selling cars too quickly isn't one of them (relatively speaking, at least).
The average car on US roads is 11.4 years old: http://www.latimes.com/business/autos/la-fi-hy-ihs-automotiv...
The average car on EU roads is 8.6 years old. In fact, in the EU only Estonia and Finland keep their cars longer than the US on average. http://www.acea.be/statistics/tag/category/average-vehicle-a...