Please stop spreading this myth. You and I had this same discussion last year.
There was never any “uppercase/lowercase” distinction.
For the sake of anyone else who hasn’t seen this, here is the number plate out of a 1943 Kubelwagen (Nazi military vehicle) with capital-V “Volkswagenwerk G.m.b.H” across the top.
And here’s the number plate from a 1959 beetle with the exact same name across the top over 15 years later, long after the factory had been returned to German control after being restarted by the British. The company didn’t become Volkswagen AG until 1960.
Even when referring to the car itself as “the Volkswagen,” it’s still a proper noun and Germans capitalize all of their nouns anyway.