Before the wholesale introduction of the Land Rover into military service there was the Austin Champ,
It had ostensibly a full set of doors as well as a canvas roof,
The doors never fitted and were almost always left in the Stores,
Needless to say the vehicle had no heater, all that it had was a small inspection port in front of the Gear Lever which funnelled engine heat into the cab,
Of course with no doors it was a waste of time and the drivers signed onto these vehicles were permanently allocated Parkas.
The champ came into its own in the summer, All of a sudden everyone wanted a drive of one
Trust me a German winter on the Sennelager training area was probably not much different from the road to Stalingrad.
Of course you don't get used to it but we were usually close enough to a NAAFI Van or the Units catering facilities (Tea Urn) to ward off frost bite.
We were lucky enough to have a Sgt who delighted the men in the morning by inviting them to do their exercises in the snow in shorts and a PT vest before breakfast.
I would have sold my soul to be back in a Borneo Jungle after a couple of weeks in a German Winter.