You could try finding an FBO willing to apprentice you but I doubt you will find one. Most places will only do it if they believe that you are going to stay on with them for the long term. An FBO has to invest a lot of time (2 years) and money (you will slow down the person training you a great deal) in training to get you ready for an A&P even with your car maintenance experience. If you don't already have a degree, you could always go for an Aircraft Maintenance degree (4 years) and knock out two birds with one stone. Otherwise, your only other option is a Part 147 school which will take about 18-24 months.

If you want to be a professional pilot, attaining your A&P would be a long sidetrack in your career. You are better off just continuing to build your hours as an instructor and getting a pilot job as soon as possible. Now if you really want to work as an A&P then the above options are the way to go. If you have any questions about being an A&P just pm me.