I wrote an update in 2014, and argued vehicle sales would “mostly move sideways” for the next few years.
Here is another update to the U.S. fleet turnover graph.
This graph shows the total number of registered vehicles in the U.S. divided by the sales rate through July 2019 – and gives a turnover ratio for the U.S. fleet (this doesn’t tell you the age or the composition of the fleet). Note: the number of registered vehicles is estimated for 2018 and 2019.
The wild swings in 2009 were due to the “cash for clunkers” program.