The biggest problem I would expect would be corrosion. Your trouble areas would be connectors and ground connections "straps with bolts to the body of the car or boot lid". The .95 volts sounds like a bad connection which can occur in switches, and fuses also.
There is probably a connector for the lid just inside of the main part of the car away from the moving body parts. It would be logical that they had to have a harness for the lid and a connector to add the lid later in the assembly of the car.