Do to certain property line restraints I'm unable to lay a concrete slab or foundation for this larger shed construction. 12'x20'. I'm using a 2"x6" galvanized steel floor joist system. The joist will be 12" OC, with joist running the 12' span, with a 3/4" plywood flooring. All this set atop a leveled 4" crushed stone base.
I'm using this shed to park a car in. (weight of car is 3600 lbs)
My question: Will this floor system hold the weight of the car? I have been unable to find any Steel load calculators online. Thanks for any help in advance.

You might find some loading info from the link I have put below, but this is something a Structural Engineer should verify. I don't understand how you don't have room for a concrete slab and how you are going to build it on steel joists. Are you putting it on a crawlspace? Just curious.

Dietrich Metal Framing (http://www.dietrichindustries.com/)