If this keeps up, Inside Value recommendation AutoZone (NYSE:AZO) is going to wind up with a few dozen shareholders owning the entire company. Still apparently taking itself private using the installment plan, AutoZone continues to harness the cash generated from very strong returns on capital into share buybacks.

Now, if we could just get a little more growth here. After all, revenue growth of just less than 6% in the third quarter and same-store sales growth of 2.1% isn't too bad. But a modest decrease in operating and net income isn't so super. Then again, we're talking about a company that has margins twice those of Advance Auto Parts (NYSE:AAP) and a return on invested capital of more than 20%.

To be fair, AutoZone won't be able to grow quite as fast as its competitors and it doesn't need to. I say "won't" simply because of the law of large numbers: You can build only so many stores (without cannibalizing other stores), and the bigger you get, the tougher it is to get that next percent of growth. I say "doesn't need to" because ongoing margin expansion and strong returns on capital should keep the cash rolling in even in the absence of stellar top-line growth.

I suppose in some ways I'm reminded of Home Depot (NYSE:HD) and Lowe's (NYSE:LOW) when I look at these two auto parts retailers. And to be fair, O'Reilly Automotive (NASDAQ:ORLY) belongs in the club, too. But the point I was going for is that as is the case with the big-box hardware stores, you have something of a choice between value/cash generation and growth. And I suppose it's also true that economic factors are going to play a role as well -- not in terms of new housing, but with interest rates on credit cards and the cost of gasoline.

When I run my cash flow numbers, both AutoZone and Advance Auto Parts seem roughly equally undervalued. So it really is a toss-up. I tend to go for the companies with a high return on invested capital, though, so I suppose I'd still lean more toward AutoZone today.

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Fool contributor Stephen Simpson has no financial interest in any stocks mentioned (that means he's neither long nor short the shares).