One of the coolest and by far the most economical racing sims I own is rFactor. Out of the box, the tracks and cars that it contains are made-up, rather than being virtual models of real world places and machines. But... it's wide open to third parties to create what are called 'Mods.' These mods, be they tracks or cars, are available as free downloads from the internet. They vary widely in quality, but many are very, very good. They cover all gamuts of racing, too, so there's something for just about everyone. I've even seen (but didn't download) a lawnmower racing mod!
Two new mods hit the virtual shelf this week, and both model mid-50s racing. One is a complete set of Indy cars, while the other is single make of a 1955 Formula One car. New additions to the set will be released one by one as they are completed.
I tried the Indy cars out at a present day rendition of Indianapolis:
I had trouble keeping up. These cars are incredibly difficult to drive, and require a smoothness that the aerodynamically winged cars of today don't. Even trying to make a very slight adjustment in course on the long straights often led to loss of control.
The F1 car was more suited to a nice vintage 1979 Silverstone:
These cars were easier to control, but again were very different in driving style from the winged cars we see today. It took a lot more braking to slow for the turns because there was no downforce to assist in keeping the tires from skidding. The tires themselves had a much smaller contact patch because they were so narrow, so there was far less mechanical grip in the turns.
Man, is this fun!