limiting maximum fuel specific energy means that everyone would be operating on and possibly over the limit
and races could be decided by lab tests (and legal disputes) after the event
although logically the fuel rules could otherwise be greatly simplified
Methanol is a very poor fuel in specific energy terms (Ethanol is nearly as bad)
use of such a fuel would encourage engine efficiency (with refuelling remaining banned)
because the worse the fuel specific energy the greater the benefit from engine efficiency in reducing fuel load
(eg current cars would need 350-400 litres of Methanol)
so using (cellulosic) Methanol or Ethanol would there would be no need to meter and record (and dispute) fuel use
and it counts as green/future, so would give an image value to the fuel companies that can access/source it