[jyl]

I would really like to see such a Formula.

Going even further, how about if, instead of each car being allotted the same amount of a standard fuel, each car were allotted the same amount of energy (X joules). This would allow teams to find the most efficient fuel - so you could have diesel cars versus high-octane racing gas care versus hydrogen cars. And eventually a team would figure out a way to power its car with dilithium crystals.