Just curious, are you just waiting for a call back, or have you actively tried to get a hold of the person you interviewed with to find out what's going on? A lot of times, service directors will wait to see who makes a follow up call before they determine who to hire. By making that follow up call after the interview, it shows the your interviewer that you have initiative and you want to come and work for them. If you haven't called anyone back, give it a try. Say something like "Hi, my name is _____, I just wanted to say thank you for taking the time to grant me an interview on ____(date), and to follow up on whether you've made a final decision on who you were going to hire to fill the position." That simple phone call speaks volumes to the people who matter (those that sign the checks) and can go a long way to getting a good/better job. Hope that helps...
BTW, you're looking for a job in an auto service shop right? Where are you looking or have you looked?