Built From the Driveway: Preston Callahan on Shop Growth, Knowing Your Numbers, and 24/7 Fleet Roadside

Preston Callahan's shop story starts the way a lot of real ones do: wrenching at 16 in the shade of a tree in front of his parents' house, then making the leap to ownership at 23, working out of the driveway and betting on himself. Today, Preston runs Callahan Auto & Diesel in downtown Mesa, Arizona, plus a separate arm focused on 24-hour emergency roadside service for trucks and RVs. In this interview, Preston walks through what it actually took to grow, moving from a small 1,850 sq. ft. space to a facility of 10,000+ sq. ft.—and the lessons that only show up once you're responsible for payroll, margins, and the "everything breaks at once" reality of running a shop. You'll hear him get candid about the mistakes that happen when you don't know your numbers fast enough, the constant balancing act between parts margin, labor margin, and staffing, and why even years in, he's still experimenting and learning (including what he calls his "Google business degree"). Links: Honest Mechanic Marketing (HMM): https://honestmechanicmarketing.com/ Callahan Auto & Diesel: https://callahanautoaz.com/