This question was asked 50 years ago by the racing guru Roger Penske so he devised a plan to see who really was the world's best race car driver.
He ordered a dozen Porsche 911s from Porsche in Germany. They all were absolutely identical. Same horsepower on the dyno, same weight and weight distribution, same tires, fuel, etc.
Their racing numbers were from 1 to 12 and each wore a different vivid color to distinguish them during the race. They looked like a bag of Skittles dropped from the sky.
Then Penske selected the champion drivers from each racing discipline to compete against each other: F1, NASCAR, Trans-Am, Can-Am, Indy Car, etc. The drivers selected were all world famous such as Emerson Fittipaldi, Richard Petty, Bobby Unser, Bobby Allison, Mark Donahue, A.J. Foyt, Peter Revson, George Follmer, Roger McCluskey, David Pearson, Gordon Johncock, and Deny Hulme.
The race was called the International Race Of Champions (IROC) and consisted of two heats of 20 laps each and took place at Riverside International Raceway.
The drivers selected their car by a lottery system just moments before the race started. After the first heat the winning car was given to the last place driver and the last place car was given to the winning driver - for the second heat. All cars were exchanged among the drivers according to how they placed in the first heat. Penske made sure no one had an advantage.
Then the racing began. I was there that day and the racing was exciting
Wouldn't this be the best way to answer this question today?