If you're new to the place, establish that you're a calm, cool, knowledgeable and useful employee that gets results for customers. Your coworkers and regular customers ought to back you up, regardless of sex. Since you actually do know your way around a car, I'd suggest being extra eager to do OBDII scans, wiper blade installs, etc. to show it off a bit. It's not much, but you'd be surprised how many people have absolutely no idea how to install their wiper blades and will be impressed when you do it for them in under 2 minutes.
