I’ve re-built a British Ford Essex engine to have a 16.51 to 1 Compression ratio, with a higher CR than the 8.9 to 1 it had originally it will naturally be more thermodynamically efficient. The only way to get greater thermodynamic efficiency was to use a different fuel. Most fuels are gases which makes storing difficult. I decided to use ethanol, because it’s used now as Flex-fuel so it’s available it’s renewable and although it’s only ¾ the energy density of petrol/gasoline at atmospheric pressure under high enough compression it has more power. It doesn’t vaporize quite as well as Petrol/Gasoline which means it needs direct or multi-point injection to be used reliably in a car, but that means it’s safer you’re not carrying round a bomb. As most cars have EFI now it’s not anything unusual.
All modern S.I. engines start with settings remembered in the ECU, settings to start the engine using it’s fuel easily. Immediately it fires it continues running with feedback from the sensors. That’s why the sensors are there, the ECU does accommodate for wear in the moving parts, but they're actually programmed to keep the engine in the most economical and powerful state of tune within the mandated exhaust perimeters.
The U.K. Government knows that burning fossil fuel is a major cause of climate change and they've all got a duty of care, that's why all the petrol for sale in the U.K has some ethanol in it, that's also why Briton has finally put some bio-fuel duty rebates in place. Essentially anyone in the UK can get a duty rebate it just has to be a 100% bio-fuel it CAN BE ETHANOL (used in spark ignition engines) or BIO-DIESEL (used in pressure ignition engines) and you must have been charged some road duty for it. The problem is buying 100% bio-fuel is difficult, the oil companies have no reason them sell them, none of the price would actually be for them. The government isn't advertising it (why would they, it would cost them revenue). The 25,000L/year allowance is designed to be just what a private individual would use for personal use.