I note that the website
www.diecast72.com includes pix of the four (?) Corgi Showcase models which are very close to 1/72 scale - the M3 halftrack, the Honey light tank, the Scorpion light tank, and the M8 Greyhound. The flaw with the halftrack is its terrible 0.50 cal MG, and that it runs on clear plastic wheels under the chassis (as does the Scorpion). However, the M8 armoured car - while flawed - is a pretty good casting, with decent (turning) wheels, and it can be salvaged:
1) Cut off the ridiculously over-sized main gun barrel, and replace with a scale 37 mm from a model kit, or from the Corgi 'Honey' mould (which is actually to scale).
2) Similarly, replace the 0.50 with a proper MG
3) Insert painted 1/72 crew figures into the turret - they can be made to fit, though you may have to cut their legs off...