On 4 Mar 2021 11:29:21 GMT, Tim+ wrote:

I was under the impression that all cars running on unleaded were burning
10% ethanol. Or are you talking about the difference between diesel and
petrol? I doubt there are any ethanol fuelled cars outside of a race track
or drag strip.

https://www.gov.uk/guidance/e10-petrol-explained

E10 means petrol contains up to 10% renewable ethanol. To date, petrol
in the UK has contained up to 5% renewable ethanol (known as E5).

E10 petrol is already widely used around the world, including across
Europe, the US and Australia. It has also been the reference fuel
against which new cars are tested for emissions and performance since
2016.