While bigger can often be better in the world of stock investment, some small-cap stocks -- stocks of companies with market caps under $2 billion -- are also worth a look as their future performance generally has more initial upside potential. There are plenty of companies to consider, but if you are looking this month, there are a few small-caps running ahead of the pack this summer worthy of a closer look: Sonic Automotive (NYSE: SAH), CarParts.com (NASDAQ: PRTS), and The Lovesac Co. (NASDAQ: LOVE). Let's find out a bit more about these three top small-cap stocks to buy in July.