After looking at open spaces to help feature the vehicles I made a few white box plans to help generate idea's and to also get some thinking room in my brain, (so cluttered).
I planned these out in 3ds max, just boxed out spaces and added a few minor details;

This was a quick stable yard idea. So the vehicles would be situated within the building and one of them would be place outside so there is a variation. This meant that the camera or the player would have to walk around and through the building to see them. I really like this idea but I would be very worried about the time it would take to make, texture and import into UDK. I don't want to be too short for time as that is a major fall back for me; time management.