If you're looking for manga similar to Boku ni Koi suru Mechanical, you might like these titles. All recommendations are made by Anime-Planet users like you!
If you enjoy seeing a lot of references to classic action (and non-action) movies in your manga then Boku ni Koi suru Mechanical and Kaibutsu Oujo might be series for you. Both do this in spades, though Kaibutsu Oujo also has a lot of game references.
Edit: Fixed the manga name. Was suppose to be Kaibutsu Oujo instead of Kaibutsu Ouji...