I have just discovered this thread and have spent the last hour devouring it. What a feast. Many thanks to all the contributors of such fascinating archive material. I cannot resist putting in my own two 'penneth. These are all photo's and/or cars that have inspired me over the years.
One of the first motor racing books I read when about 9 years old was Charles Jarrott's Ten Years of Motors and Motor Racing which covers the first ten years of the sport. In it there is a chapter on the disastrous Paris Madrid race of 1903 which spelled the (temporary) end of open road racing. I was very impressed by the following two photo', and still am.
This type of car is enthusiastically raced today of course and looks to be great fun. Here is a Panhard.
Reference has been made to the Vanderbilt Cup Races and an early competitor was this fearsome steam car. It is huge when seen in the flesh, and I cannot imagine doing 90 mph on a dirt track perched on the bar stool type seat.
To add to the Lancia Ferrari D50 series, this one is in the Ferrari Museum at Modena.
As far as best photo's of all time, this has to be up there. Fangio in a 250F at Rouen 1957. Note the haze of tyre smoke from the outer left rear.
On the subject of tyre smoke the old slingshot dragsters couldn't be beaten. As the driving instructor would say - let the clutch in gently.
A final one for the eclection which still makes my bum clench when I look at it. The late William Dunlop at speed.