Only thing I can think of is that the car is garaged over winter and covered with a tarp over the top only.
Could be the bonnet holds condensation, whereas the rest is open to dry out, and has absorbed moisture.
Regards, Geoff
That's exactly what happened when I left my AH 3000 outside for 2 months under a watertight tarp - only the aluminium panels were affected.
BTW the pimples on my 3-wheeler were much smaller than those on your bonnet. I probably wouldn't try polishing yours away.
And no, Dean, it wasn't orange peel but you are right that there was enough paint to polish part of it down (and no clear lacquer on it like on moderns
