1 [caption]: 150km east of Paris:
2 Erwin: Maybe it is time for a rest break, Herr Kolonel.
3 Haken: Nein! Keep driving. We must get die Palladium to Berlin as fast as possible!
4 Erwin: Shouldn't we have taken die zeppelin we left behind in Paris, then?
4 Haken: Ach!

By my calculations, that puts them somewhere around Châlons-sur-Marne, as it was known in the 1930s. The city was renamed to Châlons-en-Champagne in 1998.

I actually had to check that the distance I'd chosen was still inside France. European distances are a lot smaller than the ones I'm used to dealing with here in Australia.

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2020-05-30 Rerun commentary: Google Maps suggests the best driving route from Paris to Berlin actually heads north from Paris, via Roye, Cambrai, Valenciennes, then through Mons and Liège in Belgium, before reaching Germany near Aachen, then Cologne, Dortmund, Hanover and east to Berlin.

The alternative route east would go via Châlons-en-Champagne, Reims, Metz, directly into Germany at Saarbrücken, then Frankfurt, Leipzig, Berlin. This route is nearly 100 km longer. Although of course some of the roads that Google suggests probably didn't exist in the 1930s.

The eastern route also gets you into Germany a lot quicker, without any needless faffing around in Belgium, so presumably this is why Erwin selected it.