The car is the customer, and it has a schedule
Automotive retention is unusually tractable because the asset tells you when the next interaction should happen. A vehicle has service intervals, insurance expiry, warranty end, an ownership cycle and a running pattern. Almost every retention opportunity in the business is a date you can compute in advance, which is a luxury most industries do not have.
What goes wrong is not the arithmetic. It is that the dates live in a dealer management system nobody is accountable for reading, the reminders go out as generic announcements, four departments contact the same household independently, and nobody records why a customer said no. The retention routine below is mostly about fixing those four things.