AJ,
If you are on somewhat of a tighter budget, my suggestion would be to invest in internet marketing and grass roots level marketing. SEO, Yelp, Google Adwords, Google+, Facebook. Also hit the streets with business cards and introduce yourself. In the future you may add a direct mail campaign to your marketing efforts however to do so on a large scale would be very expensive. You may want to spam your area maybe once just to help you get the word out. Also something else that won't cost you as much money is CRM. Look into your data base and figure out a good speech to pitch. Something like, "Hi this is AJ Nealey Automotive. We are reaching out to our really great customers to let them know that we are moving to a bigger location! We are really excited to be able to better serve our community. We would love to have you come to our grand opening. Also with a new larger location we will be able to serve a lot people. We would be honored if you would refer us to some of your friends..."
Your ARO seems healthy however your overall GP of 53% is a bit low. 60% or better should be the target. With that being said you can survive off 140 cars a month if you raise your ARO. Even at $550 x 140 cars = $77,000. Thats a pretty healthy number.