Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of auto-supplier LKQ (NASDAQ:LKQ) were looking stronger today, gaining as much as 15% after posting an impressive second-quarter earnings report.

So what: The maker of replacement auto parts and systems delivered an adjusted earnings per share of $0.26, better than expectations of $0.25, and said revenue grew 24% to a record $1.25 billion. That figure was much better than the $1.19 billion analysts had expected. CEO Robert Wagman noted that organic revenue growth was 13.1% for parts and services, while European organic growth surged 37.8%. Management also lifted its guidance saying it now expects revenue grow of 8.5%-10.5% for the full year versus the previously stated 6.5%-8.5% and EPS of $1.03-$1.10, versus $1.00-$1.09.

Now what: Wall Street always like to a bump in guidance so the jump in share price shouldn't be a surprise. However, I'm a little concerned about the sustainability of growth in Europe as new car sales have stalled amid the recession, leading to high demand for replacement parts, so I wouldn't expect to see that level of growth continue for an extended period. With a P/E of 32 and modest growth prospects then, LKQ looks overvalued after today's rise.

Fool contributor Jeremy Bowman has no position in any stocks mentioned. The Motley Fool recommends LKQ. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.