I've been taking my older car here for smog for years without incident. I recently brought my car in for a smog and was told it failed: reason was failed "EVAP Functional Test." PA Shell charges a $180 "diagnostic fee". I decided rather than pay that fee, I would rather take my car to my regular mechanic, who specializes in my car's brand. He found an issue with the gas tank and replaced it. I then re-submitted my car to PA Shell (another fee). It again failed. I took the car back to my mechanic. He discussed the issue with another local smog shop. A certain procedure is required on older cars (like mine): The tech is supposed to clamp the end of the hose leading to the Charcoal Cannister and pressurize the gas tank with Nitrogen via the EVAP test tool. This tests for pressure loss. A retest was performed, properly, at this other smog station. My car PASSED. I'm quite upset with Palo Alto repair and will take my car elsewhere.