2 more points I didn't make that have been trotting through my mind.

1. I wondered whether KMX was or was not vulnerable to an economic slowdown, and guessed that it wasn't very vulnerable. I wondered whether it was maybe even the opposite, able, in other words, to take advantage of a weak economy (or antifragile, to use the term ccined by Nassim Taleb.)

On the one hand, 60% of their clients use financing provided outside of CAF (Carmax Auto Finance.) If banks become unwilling to lend to used car buyers, is this a problem for Carmax?
I don't really know for sure what the answer is, but I suspect the answer is that it is at the 'durable' middle of the spectrum fragile-durable-antifragile.

It is true that Carmax had a big earnings miss last quarter, which many analysts attributed to the beginning of an economic slowdown, but I'm not so sure. The big problem for Carmmax was that there were just no a lot of used cars available for sale, with the same thing true for new cars. If automakers are not producing cars (because of supply chain disruption, lack of chips, lack of labour, etc.), then people will not trade in their used car to buy a new one. High interest rates don't help either. But if there's a slowdown, both of these problems will ease, and I think Carmax's unit sales will bounce back nicely, despite the recession.

I can't find data back far enough to see how their revenue and earnings fared in 2000 and 2008, which would be helpful.

The other major influence on their earnings right now is the recent increase in interest rates. I'm not sure how that one will play out, either. Carmax has the capacity to finance their customers' purchases through its financing arm, and if banks back of from car loans, CAF can potentially take up the slack. Since CAF is a significant part of Carmax's overall earnings, this could potentially end up pushing more Carmax customers towards CAF, and since Carmax has solid finances going into the recession, they probably have the financial capacity to do this.

These are the 2 aspects that I need to read more about, Carmax's past recession performance and its current capacity to expand its role in financing its customers' purchases.