I tried to stick a magnetic emblem to the trunk. To my amaze, it doesn’t stick!! Then I tried every parts of the car and figured out that only the side panels, doors and the top part over the windshield are magnet attachable. I know the bumpers are made out of plastics. But how about the trunk, hood, and the part on the side of the windshield?

 

I had a similar situation happen to me not long ago. I was at a funeral recently (thank goodness not as the guest of honor) and tried to put the magnetic funeral flag on the Roadster. It turns out the trunk is made of fiberglass and the hood is aluminum. Fenders and doors are of course, steel. Interesting side note, all the funeral home employees had to come out to see the Z. It was also a real chore keeping the car at funeral procession speed----but I did it.

 

Most cars today use very little metal/steel. They use aluminum, plastics, and various composites. Reasons for less metal vary from weight reduction, anti-corrosion,durability etc. But, bottom line is as time goes on you will see less metal in cars.