Ethanol is more powerful than petrol even though it has less energy density. Simply because it is higher octane and has an oxygen atom in it's molecule. You just have to build an engine to use it.
FFV's are petrol cars that have their fuel pump and injectors uprated, they've also supposedly had any other components that wouldn't last long bathed in ethanol uprated. Even so hundreds of people in Brazil and in the US. don't care, they just use ethanol or e85 in the petrol car they’ve already got, because iethanol cheap and the car makers made the FLEX-FUEL engine so low compression that they do poor mileage, I for one can't think why anyone would do that the sensible thing to do would be to make the compression as high as possible. Obviously they think e85 won't hurt a normal car much in the time they'll keep it. Modern petrol cars are computerised and injected and the ECU will take care of the timing change and the volume of the squirt of fuel. Although the check engine light will come on, this is only because the O2 sensor is detecting more O2 than it expects. You can, but you shouldn't you can do that because the modern ECU has three modes. Start-up mode, then it runs off programmed settings. Running mode when it runs off information the sensors give it so it can accommodate how warn the engine is keeping the emissions legal even at cost of HP. Acceleration mode, when the engine gets a Extra squirt of pure fuel. Whatever the oil companies say Petroleum (Petrol/Gasoline) wasn't what the Otto cycle engine was designed for, just that it's primary fuel was banned in Prohibition. It can't do better MPG than its engineered compression will allow. Alcohol was the primary fuel for cars, but in the many years petrol has been king, the Otto cycle engine has been optimized for petrol.
Bio-fuels are slight solvents, that's why they clean the whole engine, they clean away all the bad things fossil fuels has left behind in the years you had to use it. With diesel engines you just put bio-diesel in change the fuel filters after a week and away you go. With petrol engines you'll be using ethanol. Ethanol is very hydroscopic it wants to grab every molecule of water at can. Changing the fuel filters after a week should be fine too.
Now you've decided to use ethanol you need to optimise the engine by fitting domed pistons to increase the compression. Otherwise you'll have only done half the job. Whatever you do it'll never pink, higher compression means greater mileage, and more power
Fossil fuels are a obviously finite resource eventually we'll run out, but any bio-fuel is a renewable resource they'll be there to use as long as we can think up ways to make them. As I read the UK duty regulations any one should be able to claim back the duty on any bio-fuel you've paid duty on up to the point you have used more than 25,000 litres per year.
Originally cheap pre-war cars were modified by returning American second world war servicemen into hot-rods because servicemen had a pocket full of back pay, and no new cars to buy. This was because every industry including the Detroit car makers had been making war goods. These cars used Gasoline as the standard fuel but, it’s very high carbon footprint. This was the late forties petrol was cheap and there was no problem using lead to make the petrol usable. The Ford model ‘T’ was built at a time when ethanol was cheap and legal even the recommended fuel by the factory with the expectation it would be run on some Moonshine sometime, because every farm had a still and Henry Ford was forcefully against ‘his’ cars running on imported fuel. Gasoline is only high carbon footprint because it was formed in the carboniferous age. Generally people didn’t know about Climate change because they had other things to think about. The political outlook was so bleak being just having fought a war against Fascism and now being at the start of the ‘Cold War’. Some of these people had just left the service where people who where willing to try new things to make these older cars go fast. Some of them had acquired with the expectation it would be run on some Moonshine sometime, because every farm had a still and Henry Ford was forcefully against ‘his’ cars running on imported fuel. Gasoline is only high carbon footprint because it was formed in the carboniferous age. Generally people didn’t know about Climate change because they had other things to think about. The political outlook was so bleak being just having fought a war against Fascism and now being at the start of the ‘Cold War’. Some of these people had just left the service where people who where skills to modify in the military. Some wanted to have the luxury they had been missing out on. Often that meant putting a V8 into a model ‘T’, and then re-trimming the whole interior. Some of these people had used supercharging, injection or Nitrous in the service. Skimming the head or putting domed pistons in the engine to raise the compression was of little use because petrol pinks at such a low compression but at the time petrol was made higher octane with additives which are illegal now.
Now by making use of the extremely high octane level of any Ethanol fuel blend. As well the fact that ethanol contains oxygen, car owners can save money and for the first time make the Greens happy. Ethanol is carbon neutral and can be made anywhere. E100 comes mostly from the Brazil where it's a bi-product of the cane sugar industry or the corn belt in the USA. where it's a bi-product of making brewers grains animal feed, and that makes a nonsense of the whole food v fuel debate that the Oil company agents bang on about, but ethanol could in fact come from anywhere and be made from nearly anything organic.