You need to remember if you have a few years of increasing car sales it will follow a few years of decreasing car sales. If your normal loyal customers bought new cars in the mid 90s so to say(period of increased) the following years where they are still driving their new cars you won't have as many sales(period of low). Then 5-7 years down the line depending on their loan and if the car held up well they will be back to buy another(years of increase again). So as long as They are still selling cars and breaking even if not profit they're good in the long run.
