There isn’t a built-in system like that but there doesnt need to be since we have Blueprints. You bring your vehicle base(chasis and wheels) and create your vehicle BP and then attach any other part you like as separate components inside that vehicle BP. Here’s a proof of concept: https://dl-web.dropbox.com/get/ue4/mix/ch_4.jpg?_subject_uid=88945358&w=AACivK1U_8gDRB08IHpqKrokKOd7XXzNlR6qf-QSnQ0_iA
The body and the wheels are imported as a single skeletal mesh and that is the actual vehicle. Windows, lights, interior, etc. are imported and attached as separate static meshes in the BP.