If your oil returns have a slight leak the full synthetic oil can weep onto exhaust and gives a interesting odor.
If one of your convertible top hydraulic lines leak around the tiny o-rings it can give you a Pentosin fluid smell.
I had my 2005's top replaced under warranty and it smells like a new car inside. So I am just guessing about a top smell.
No idea about a melted crayon smell unless you haven't burnt off the exhaust sealant excess, the sealants used in construction, or some other materials in or around the exhaust system. Been a long time since I burnt a crayon
If its a burning smell I would think any of the above are closer than rotten cabin air filter, ac, or similar scents.

Oh I too have a slight whiff of antifreeze at start up. Of course its had that since I've owned it for over 5 years without a heater core failure or leak.
When it goes I'll replace and see if it cures that start up odor.

Cheers!