Since moving to San Marcos, I have always gone to Harbison's to get my car's state inspection done. I have never encountered a wait, as I have always been the only car needing inspection when I arrived. The process is very quick, and I am usually there for only 10 minutes while the guy test drives and looks at my car. The only drawback is that there is no air conditioned place to wait while your car is being inspected. You can either sit in the outdoor seating area under an umbrella for shade, or you can sit in the garage near a fan.