After all this discussion did someone really go and buy such thing for a test?

My opinion is buy a giant metal toolbox and lock ur laptop in it when u leave ur car! Just like lorry dirver which lock their valuable tools in their tools box. Even the thief sense ur laptop in it they will still need to carry a Giant Plyer to cut it open! And those plyer will be around 70cm-100cm tall very noticeble if carry around!

It would be more difficult than just hiding it at the back or under the seat right! Besides that holding a giant plier on the street, will attract a lot of ppl and police also has the right to arrest those ppl or question them on sight (base on my previous experience).