Summary Merged the body halves in Meshlab to make it easier to print, and without the need to glue the printed halves together. CuraEngine says the result is not manifold yet it sliced OK anyway, with the exception of an approximately 2mm x 15mm slot (missing material) on the rear bumper. Slic3r does not have this particular slot of missing material but does exhibit other small glitches in the surface. Still working on getting the tires and motor to slice, so far no luck. Instructions Merged the two body halves using Meshlab.