Six aftermarket companies–the National Auto Parts Association (NAPA), AutoZone, Advance Auto Parts, CSK Auto , CarQuest and Pep Boys–have approached the Automotive Aftermarket Industry Association to develop an initiative to promote … Three-quarters of auto parts sold in the United States are purchased as part of professional repair service, while the DIYer accounts for a declining share. Most parts suppliers at best break even on wholesale business, Handschuh said. …