Investors looking for stocks in the Automotive - Original Equipment sector might want to consider either Magna (MGA) or Spartan Motors (SPAR). But which of these two stocks presents investors with the better value opportunity right now? Let's take a closer look.The best way to find great value stocks is to pair a strong Zacks Rank with an impressive grade in the Value category of our Style Scores system. The Zacks Rank is a proven strategy that targets companies with positive earnings estimate revision trends, while our Style Scores work to grade companies based on specific traits.Currently, Magna has a Zacks Rank of #2 (Buy), while Spartan Motors has a Zacks Rank of #3 (Hold). The Zacks Rank favors stocks that have recently seen positive revisions to their earnings estimates, so investors should rest assured that MGA has an improving earnings outlook. However, value investors will care about much more than just this.Value investors also try to analyze a wide range of traditional figures and metrics to help determine whether a company is undervalued at its current share price levels.Our Value category grades stocks based on a number of key metrics, including the tried-and-true P/E ratio, the P/S ratio, earnings yield, and cash flow per share, as well as a variety of other fundamentals that value investors frequently use.MGA currently has a forward P/E ratio of 8.68, while SPAR has a forward P/E of 22.76. We also note that MGA has a PEG ratio of 1.02. This metric is used similarly to the famous P/E ratio, but the PEG ratio also takes into account the stock's expected earnings growth rate. SPAR currently has a PEG ratio of 1.52.Another notable valuation metric for MGA is its P/B ratio of 1.78. The P/B ratio is used to compare a stock's market value with its book value, which is defined as total assets minus total liabilities. For comparison, SPAR has a P/B of 2.92.These metrics, and several others, help MGA earn a Value grade of A, while SPAR has been given a Value grade of C.MGA has seen stronger estimate revision activity and sports more attractive valuation metrics than SPAR, so it seems like value investors will conclude that MGA is the superior option right now.Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Magna International Inc. (MGA): Free Stock Analysis Report Spartan Motors, Inc. (SPAR): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research