I'm something of an amateur historian. In the field of historiography there is nothing as good as a primary source of information. When I was 14 years old I personally listened with wrapt attention and dubious assessment to the reminiscences of Alexander Kerensky, the leader of the provisional government which had overthrown the Russian Tsar in 1917. I've talked to a lot of old folks in my time. It's been very interesting.
Old cars are also witnesses to history.
You can see Woodrow Wilson's Pierce Arrow at Staunton, Virginia. Ford Phaeton is at Hyde Park. If auction catalogues are to be believed, almost every prewar Mercedes cabriolet has been driven by Hitler's girlfriend, Eva Braun. The old cars of everyday people are just as interesting. Unrestored vehicles from the '40's might have gasoline rationing stickers on their windows.