If you need to you can build a wood floor rather than a concrete floor and still park your vehicles on it. I had a 24x24 demo on my sales lot that I parked my vehicles in for years. We built it on a wood floor because we knew we it would need to be moved at some point. Eventually I started parking my vehicles in it and the floor held up just fine.
It was 3/4 in plywood over 2x6's 16 inch on center with pressure treated 4x4 's every 48 inches sitting on 4x4x16 mobile home pads spaced 48 inches apart. In other words it was a pretty standard wood floor. I parked a 3/4 ton dodge diesel truck on one side and my car on the other.
Eventually the floor started to move from the blocks settling. But I had planned ahead by screwing the plywood floor down so I could remove sections to reset the blocks as necessary. Eventually the floor began to wear from the dirt and tires so I put a second layer of plywood in the tire track area.
All in all it gave me perfectly good service for about 10 years till we went out of business and sold it. If you wanted to upgrade the specifications to make it a little stronger I would start with going 12 inch centers on the 2x6 floor joists. And of course make sure your blocking is on firm ground.
It was 3/4 in plywood over 2x6's 16 inch on center with pressure treated 4x4 's every 48 inches sitting on 4x4x16 mobile home pads spaced 48 inches apart. In other words it was a pretty standard wood floor. I parked a 3/4 ton dodge diesel truck on one side and my car on the other.
Eventually the floor started to move from the blocks settling. But I had planned ahead by screwing the plywood floor down so I could remove sections to reset the blocks as necessary. Eventually the floor began to wear from the dirt and tires so I put a second layer of plywood in the tire track area.
All in all it gave me perfectly good service for about 10 years till we went out of business and sold it. If you wanted to upgrade the specifications to make it a little stronger I would start with going 12 inch centers on the 2x6 floor joists. And of course make sure your blocking is on firm ground.