I second this!
In fact, as British armored cars go, the Humber armored car would be an excellent choice, but for some reason there has been talk for the American built T17 Staghound (used by the British), which is a late war armored car. However, the Humber armored car would be a far better choice for several reasons already mentioned.
Just as emmanuel pointed out, the Humber was one of the most widely produced and used armored cars in the British Army, and saw combat with the British and Commonwealth from 1941 until 1945 - and maybe post war as well.
Also, and important to note, the Guy armored car from 1939 to 1940 was the predecessor of the Humber Mark I, and these two armored cars have so many of the same features that I don't think it would be at all difficult for Rubicon Models to work their magic and create a Humber + Guy kit. That is, a plastic model kit that could be assembled to make the Humber Mk.I, II, III, IV or Guy armored car. That would be just fantastic wouldn't you agree?! A single plastic model kit that could assembled into an armored car that was used from 1939 to 1945.
This would also fill in a void in a lot of gamer/model collections since there are no good plastic model kits for a good British/Commonwealth armored car. Especially a significant one like the Humber.
That being said, it is easier to say than to do because to be honest, even though they all look like they have common features, and it looks like it would be possible to make an all-in-one plastic kit, it of course depends on the much finer details.