The latest version of F1 1965 is out, together with a '65 season track pack and it's marvellous.
If you like historic open wheel racing but haven't checked out these pocket rockets yet then you should. They are very,very sweet to drive and provide loads of feedback. Not much grip or power but plenty of fun.
The AI is extremely well done, which means they are simply crappy rather than psychotic - they'll punt you in braking zones and back off for no reason in fast corners, but the mod team have done a great job using what rFactor gave them to work with.
The frame rates are superb, my PC is ancient and I can run a grid of 24 cars at pretty high graphics settings.
Check it out if you like historic cars, the download links are in the usual places.