Problem with surface to solid model for CFD

Hey Guys,

             This is my first ever attempt at making a surface model for a FSAE car body. I tried different ways of making this part but for some reason the final thickening of the surface is failing and hence, I am not able to get a solid body that I can use in a CFD analysis. I think the problem is overlapping surfaces or lofts but I am really lost on how to solve it. I don't even know if that is the actual problem. If someone could take a look at the part and help me solve this problem and telling me what I did wrong it would really be appreciated. I have attached the two versions of the part. I would ideally one final solid body that I can save as a step file and use in a CFD analysis.

Looking forward to your solutions.

Thank you so much.

SolidworksSurfacing