[ainarssems]

I don't see why e10 would burn less efficiently than e5 or pure petrol. If it was not burning efficiently it would somewhat defeat the purpose of reducing emissions although main purpose is to go in the direction of more carbon neutral and renewable.

The main reason for increased consumption is that ethanol has lower energy density than petrol so you need to burn more of it to get the same amount of energy. Petrol is about 34MJ/l and ethanol is 24MJ/l so e10 blend will have about 33 or about 3% lower energy density and consumption will be about 3% higher than pure petrol or 1.5% compared to e5.