I would really, really like to know more about the source of the bio-ethanol before it is blandly touted as 'greener'. Usually, it is not -esp. if it diverts lands from food crops.
Amongst the most obvious/ egregious such claim is Bioethanol sourced in the US, which is all from corn - and for which, it takes 2galls of diesel in the farming, to deliver nearly 1gall of bioethanol (& this is a matter of long record.)
That's simply bloody idiotic, from every perspective. (but the subsidies! ah, the subsidies... is why)
ETA: Alcohol has very slightly less than 1/3rd the energy density of pump petrol, so we'll all use slightly more as result. E10 will be about 93% energy of a litre of E0, or about 96% of E5. So the extra ethanol content is going to be outweighed, on average, by about 1% more total fuel consumption averaged across the fleet fro a given distance travelled (mutatis mutandis) if my rough mental arithmetic is about right. Great: no net CO2 gain after all ... where does the alcohol come from again..?