In my experience, Germany is a fairly cool country. June temperatures in Germany were like late September temperatures in the Adirondacks, when I would visit our offices in the state of Hesse in western Germany. Germany is located between the Alps to the south, and the North and Baltic seas to the north. The cold North Sea dominates German weather systems most of the year. Germans probably tolerate cold weather a little better than we do, as a result.
In the 1950s as today,distances traveled in winter were short: home to work and back again, or home to market and back again. Long distance travel in cheap cars like the poorly-heated early VWs was pretty much restricted to August vacation times when the weather was relatively warm.