"I am looking to retain my current schedule as much as possible, which is currently Monday through Friday from 8:00 - 5:00. I understand with an auto shop that there will occasionally be times when we need to put in more hours to finish up a project."

Even though most auto repair shops are open 8-5, there will be days you need to arrive much earlier or stay later. Being a team player means sharing the responsibilities and tasks, helping out your co-workers when the shop is busy, or they need assistance on a repair job. A good attitude goes a long way.
Before answering scheduling questions, it's important to be clear on the interviewer's expectations. If you haven't had a chance to clarify their scheduling needs, now would be the perfect time to ask!
Consider asking, 'What are the scheduling expectations for this position?' If they expect you to work 12 hour days, it would be important for you to know that before you respond with, 'Absolutely! No problem!' You want to be sure that you can meet their expectations.
If it turns out their schedule expectations won't work for you, think about what you CAN offer and see if you can meet in the middle. It's much better to discuss these things in an interview than for you to commit to a schedule that won't work for you.
Keep in mind that, in most states, an employer cannot demand that an employee work more than 44 hours per week.

"I am definitely looking to work full time, but I know that busy times and unexpected things pop up now and then. I'd be willing to pitch in and pull my weight when it comes to overtime occasionally. I am a team player and understand that sometimes more hands are needed for longer hours during busy weeks."