Reference your "If Americans call the bonnet the 'hood', what do they
call the hood?"
The "top"! This makes total sense because that is what it actually is
"the top of the car". The "bonnet" is really "a hood" as it is NOT some
woman's hat but "hoods and/or covers the engine" and "the hood" is in
reality "the top". Of course "the boot" is in reality and practice "the
trunk" because that is where you store and carry your luggage, not just
your foot wear, when travelling.
Leave it to the English and Kiwi's to screw up the English language --
especially when it comes to identifying parts of a car! This is probably
because the English and Kiwi's were still riding horses and buggy's
around their little islands while Americans were driving Model T Fords
across the 5,000 kilometres of the USA!
I hope this clarifies matters for all members of the list

Regards
Bill