´Tonneau´ is correct for any sort of cover, partly or entirely of the tub.
The soft, tarp, cover used to be an almost universal weather protection for runabaout vintage/classic sports cars/cabrios.
The hard cover was mainly derived from ´Le Mans´ type spiders (no/low windscreen) with the passenger side cover and the aero bulge only behind the driver.
The latter is surprisingly difficult to find for the ZZW30 but they áre about. Here sc threads
Looking for Tonneau Covers
Finally got around to cleaning the car and de-badging. Here's the tonneau cover without the crazy wing. I took some pictures of the latches so you can see how it fits. - The latch: - - Possible space for harddog rollbar?
The tarp one you will need to DIY like I did.