The Markforged parts are stronger than normal FDM parts in the X/Y directions, but that's where that sort of print is strongest anyway. I don't think they're any stronger in the Z direction, across the laminations, which is where all prints of this type are weakest. So if that's the process you decide to use, design accordingly. To make parts as strong as normal carbon fiber parts, print (or machine) the molds instead of the parts and lay up the carbon fiber against them, using the same epoxy resins and techniques used to build boats. If you want to make more than one car, this will be a lot cheaper as well.

Andrew Werby
Juxtamorph.com