I understood peak car to mean total number of cars, not cars per capita. (wikipedia seems inconsistent on this point but does indicate per capita, so I apologise)
Obviously this doesn't apply as far back, then, but it still applies. I'll leave the calculation as an exercise.
This is really long-term trend. First they thought at would plateau at 1 car per household, then 2 cars per household, then 1 car per licensed driver, and as it blew through all those "round numbers" (in the US) no one really knew where it was going to stop. Cars per capita (or per household or per driver) peaking is a big deal even if population doesn't peak for another few decades.
Obviously this doesn't apply as far back, then, but it still applies. I'll leave the calculation as an exercise.