Need a car part or an accessory to give it personality? Since 1903, when Sears dedicated a portion of its catalog, the automotive after-market grew into a billion-dollar juggernaut. We visit Auto Zone, the retail leader, whose largest store carries 25,000 parts. At SO-CAL Speed Shop, a sedan is transformed into a hot rod. Achieving $100-billion in annual sales didn't happen overnight, but largely on the shoulders of three entrepreneurs--cartoon characters Manny, Moe, and Jack, who were real people. In 1921, they opened their first store in Philadelphia--Pep Auto Supplies. By developing brand names, carrying key parts, and providing hands-on service, they set the standard. Finally, we look at odd products sold by auto stores, discover how Armor All transforms dull interiors into brand-new, and how a tire sealant named Slime may replace the spare tire.