Some lightening works done on a Ford Escort. The pictures with the holes seem to come from the front bonnet hinge, back bonnet hinge and wipers. Interesting. Some of this could not be implemented in our car as the current design does not use so much material. Especially the hinge for the hatch. Nevertheless, it gives some ideas of what people go through to make their cars lighter. Suddenly I feel vindicated
Hinges seemed obvious targets as the are typically thick. In design, they need to provide rigidity when the bonnet/hood/hatch is moved. The two hinges provide a movable point and bears the load. Thefore, rigidity and stiffness is a requirement. If we look at door hinges, they are the more thicker and bulkier of the rest. The load is entirely on them until the door is closed. When a door is closed, the load is shared around the door sill and not on the hinge alone.
What I have done on my car much earlier was removal of the hinges and made more holes.
The lightening work was not as extensive as the top two. The M6 bolts on the top hinge were replaced with Pro Bolts Aluminium ones while the bottom was a Titanium one. I chose Ti rather than another Aluminium as I was worried that the torque was insufficient against the aerodynamic force on the top bonnet. So the Ti bolt gives me the ability to tighten it up, whereas if it was Aluminium, I could easily damaged the thread of the bolt.