O'Reilly Automotive (NASDAQ:ORLY) is a relatively small competitor when you compare it with larger rivals like AutoZone (NYSE:AZO) and Advance Auto Parts (NYSE:AAP). But while any discernible competitive advantage is lacking, it is a little difficult to argue with results.

On Thursday, O'Reilly said that sales climbed 16.5% in the fourth quarter to $427.6 million, boosting net income by 19.2% to $28.5 million, or $0.51 per share -- a few pennies ahead of estimates. Meanwhile, same-store sales increased a healthy 8.5%.

In recent quarters, bad weather and high gas prices had hurt the auto-parts industry. But at some point, consumers would have to come back and spend money maintaining their cars. Those postponed expenditures may have helped boost O'Reilly's fourth-quarter results. Last week, Advance Auto Parts gave a similarly strong fourth-quarter report.

Looking ahead, O'Reilly expects to earn $0.56 to $0.58 per share in the first quarter, compared with the analyst estimate of $0.56. For the full year, the company anticipates that EPS will climb from $2.23 in 2004 to between $2.55 and $2.63 for 2005. The analyst estimate for the year is $2.58.

The company also expects to add approximately 160 new O'Reilly stores during the year, on top of the approximately 1,200 stores currently in operation.

Picking a best player in the auto-parts game is tough. Some might prefer AutoZone's size and its operational efficiency, while others might prefer the growth at Advance and O'Reilly. I like O'Reilly simply because it had the Gates belts I needed when the other shops didn't. But if you're interested in these businesses, be sure to check out James Early's commentary on the auto-parts wars, as well as other related Fool coverage:

Fool contributor Jeff Hwang owns none of the companies mentioned above.