Not knowing the intricacies of owning a used auto dealership, I would think that building a great brand and loyal customer base would focus on understanding of certain cars and becoming a sort of expert in them to be successful.
Given that you're in Eastern Ohio (and not, say, Dallas, TX or L.A.), I'd focus on trucks, but also I think there is a resurgence of American iron. 70s-90s RWD sedans and coupes. You could find cheap, V8-powered Buicks and Oldsmobiles for example, clean them up (light body work and mechanical repairs on the cheap), and sell them. Local sales are obviously good, but focus on making whatever you sell look as good as it possibly can for internet sales..
I am always partial to stick-shift cars...