I prefer 'nave plate'. I think a knave plate is something a varlet eats his dinner off...
There are so many papers and books written on historiographical method and use of language that it can make your head spin. This topic is, really, history of science - more specifically, history of engineering - and the encroaching danger of the search engine is as true here as it is with any historical discipline. As is ever the case with history, it all depends on who's doing the story telling, and why they're doing it. Without taking sides, I'd suggest there are two views to take:
Firstly, that of 'usage' rather than 'definitions' - the ahistorical pathway. It's worth noting that dictionaries do not give definitions (unless taken as dictionaries of historical record, e.g. The Oxford English Dictionary) - they record common usage. Meanings change over time - a good example is 'standard', which used to mean of high quality but now is taken as meaning of base quality. 'Hub cap' itself has, to all intents and purposes, replaced 'nave plate' as the pressing which fits over the lugs on the wheel disc itself; whereas as others have pointed out, its older and more correct engineering usage refers to the smaller metal cap that fits over the hub nut at the end of the axle. Following this path would require that modern common usage is applied, whereby the nave plate becomes the hub cap, AC's hub cap becomes the spinner and their change-speed-lever becomes the gearstick.
The second view would be to follow a more historically sympathetic pathway. Whig history (as described by Butterfield) is exemplified by 'looking back' at the past from a modern viewpoint, and from that viewpoint applying modern mores and meanings to past events and people. This can be extremely problematic*, especially in terms of terminology. To use an example from my own field of the history of medicine, if you were placed in the C17th and told someone they had Tuberculosis, they wouldn't have the first clue what you were talking about. If they told you they were suffering from Consumption, that might make more sense...
So it comes down to choice - do we follow AC's definitions of what the parts of their vehicles were called when they were made, in a way that someone in the AC design office or on the shop floor of the nineteen-fifties or sixties would understand: or do we apply modern, or what some would view as plain incorrect words to these parts? My preference would be to remain true to the designers and builders of the C20th, but that doesn't necessarily ease the process of communication.
Sorry for the history lesson, but it's really interesting when you get into it.
Roger
*e.g. the difficulties around the concept of modern-day government apologizing for slavery in the C18th, for example.