I think great customer service is the most effective kind of marketing imaginable.
I always get tires, brakes and alignment done at Wheel Works in Walnut Creek. Last week I went in to have a slow leak investigated on the mini-van. After the inspection, they brought me out to the shop to show me the damage and explain in detail what had happened (nail through tire) and show me the significant sidewall damage that meant the tire couldn't be repaired. I appreciated the fact that they took the time to demonstrate the issue, rather than just telling me I needed a new tire.
This week, I took the Civic in because it was pulling to the right. They had the car for 2 hours. They put it up on the rack and inspected the alignment, they road-tested it, and they rotated, balanced and topped off the air in all 4 tires. No charge. They could have charged me for the labor, but they didn't.
I think they recognize that good service breeds loyalty. Damn right. I will continue to bring both cars to Wheel Works as long as their service remains top-notch.