Ooooh, maybe a mile a gallon

.
Nearly forgot the fire service (sorry Jeff

). Along with all those Jimmys etc. that provided cover for half of Europe post-war there were a few more peculiar jobs scattered around the world:
I believe this one's in Austria:

And may well be the same vehicle as illustrated here (2/3 of the way down the page:
Nice MV pictures.
These 2 are delightful:
All those tank chassis & carriers lying around after having the armour stripped and being used on Autralian farms might be a worthy line of enquiry too.
Cheers,
Adam.