Two factors often determine stock prices in the long run: earnings and interest rates. Investors can't control the latter, but they can focus on a company's earnings results every quarter.We know earnings results are vital, but how a company performs compared to bottom line expectations can be even more important when it comes to stock prices, especially in the near-term. This means that investors might want to take advantage of these earnings surprises.Hunting for 'earnings whispers' or companies poised to beat their quarterly earnings estimates is a somewhat common practice. But that doesn't make it easy. One way that has been proven to work is by using the Zacks Earnings ESP tool.The Zacks Earnings ESP, ExplainedThe Zacks Earnings ESP is more formally known as the Expected Surprise Prediction, and it aims to grab the inside track on the latest analyst estimate revisions ahead of a company's report. The idea is relatively intuitive as a newer projection might be based on more complete information.Now that we understand the basic idea, let's look at how the Expected Surprise Prediction works. The ESP is calculated by comparing the Most Accurate Estimate to the Zacks Consensus Estimate, with the percentage difference between the two giving us the Zacks ESP figure.Bringing together a positive earnings ESP alongside a Zacks Rank #3 (Hold) or better has helped stocks report a positive earnings surprise 70% of the time. Furthermore, by using these parameters, investors have seen 28.3% annual returns on average, according to our 10 year backtest.Most stocks, about 60%, fall into the #3 (Hold) category, and they are expected to perform in-line with the broader market. Stocks with a #2 (Buy) and #1 (Strong Buy) rating, or the top 15% and top 5% of stocks, respectively, should outperform the market, with Strong Buy stocks outperforming more than any other rank.Should You Consider Penske Automotive?The final step today is to look at a stock that meets our ESP qualifications. Penske Automotive (PAG) earns a #3 (Hold) nine days from its next quarterly earnings release on October 27, 2021, and its Most Accurate Estimate comes in at $3.68 a share.Penske Automotive's Earnings ESP sits at 5.24%, which, as explained above, is calculated by taking the percentage difference between the $3.68 Most Accurate Estimate and the Zacks Consensus Estimate of $3.50. PAG is also part of a large group of stocks that boast a positive ESP. All of these qualifying stocks can be filtered by ESP, Zacks Rank, % Surprise (Last Qtr.), and Reporting date.Using the Zacks Earnings ESP to your advantage is just the start. Make sure to check out the Earnings ESP Home Page for even more earnings-related tips and tricks to design a winning investment portfolio.Find Stocks to Buy or Sell Before They're ReportedUse the Zacks Earnings ESP Filter to turn up stocks with the highest probability of positively, or negatively, surprising to buy or sell before they're reported for profitable earnings season trading. Check it out here >> Time to Invest in Legal Marijuana If you’re looking for big gains, there couldn’t be a better time to get in on a young industry primed to skyrocket from $17.7 billion back in 2019 to an expected $73.6 billion by 2027. After a clean sweep of 6 election referendums in 5 states, pot is now legal in 36 states plus D.C. Federal legalization is expected soon and that could be a still greater bonanza for investors. Even before the latest wave of legalization, Zacks Investment Research has recommended pot stocks that have shot up as high as +285.9%. You’re invited to check out Zacks’ Marijuana Moneymakers: An Investor’s Guide. It features a timely Watch List of pot stocks and ETFs with exceptional growth potential.Today, Download Marijuana Moneymakers FREE >>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 Penske Automotive Group, Inc. (PAG): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research