How many of the current drivers could even drive the old cars?
I remember several years ago when Dale Jr took one of his old man's cars for a few laps, and commented on how he couldn't believe how badly it drove and handled compared to the modern stuff. If I remember right, he stated how sore his arms were fighting with the car for those few laps, and that was still back when he was still driving. The kids they call "drivers" today would never make it 500 miles in the old cars.

Different cars, different drivers, different drive trains, and a different time. Its probably better if we just keep wondering.