I think you can, because there are some mods that use automation engines, since it's easier to make, it's probably one of the files after you export the engine/vehicle/contraption. Don't exactly know as I'm not an expert
The creators of Automation have stated that you cannot export only the engines from Automation. however, as SKB stated, there are mods that use engines created in Automation, so it's obviously possible. Find someone that's used an Automation engine in a separate mod, and ask them how they were able to export the engine.
follow this tutorial, but take the engine from your exported car: https://www.beamng.com/threads/tutorial-porting-engines-and-other-parts-inbetween-vehicles.28730/