Grizzly, that's a great start! I wanted to chime in to say don't lose hope. You're not out of luck with a single, even one that you want to park a car in. There are some great single car and small shop projects like a few that have been posted... "dubber's single", eric's "Workshop 88" (not parking but great organization).
I have a single about your size, and I have just started to make something of it. Check out my thread in my sig, but it still has a long way to go. The first thing I'd ask you is how big is your GF's car? I'm able to park our car (Mazda6) in the garage and still have room for a bench on the back wall, with a table saw tucked underneath. I had to employ a little creative use of overhang, but things seem to work out nicely, and I have a permanent bench.
Some storage above the door if you have room is a fantastic way to save space. I had JUST enough room for winter tire shelves. After that, get some hooks on those walls, and some cabinets or shelves with storage bins around the outside and you'll be in good shape. This is something that you can definitely work with, even if it does mean you'll have to move the car to do most work. Lots uf us get by that way.

Welcome to the group!