Hate said:
shame its knock rating is so poor
I expected the opposite
Taken from PH
It's 5% alcohol (ethanol). Ethanol contains oxygen so can be seen as already partially-burnt fuel... burning ethanol produces less energy than burning the same molar quantity of ethane (the relevant hydrocarbon).
However ethanol has a higher knock resistance (octane number) and thus can be raised to higher compression ratios in engines without detonation. Higher compression ratios allow higher power outputs.
For turbo engines, the increased knock resistance will allow the ECU to maintain higher boost levels without detonation, thus producing greater power outputs in less than ideal conditions (i.e. high ambient air temps, etc.).