Added Mazda UK statement clearing use of E10 in all RX-8 models in the UK.
Latest position from the GOV.UK website on the introduction of E10 fuel:
https://www.gov.uk/government/consultat ... -responses
Government decision on E10 petrol
In line with the feedback received to this consultation, we can confirm that we’ll introduce legislation as soon as possible to require fuel suppliers and retailers to introduce E10 petrol in the standard 95-octane petrol grade by 1 September 2021. We’ll also require the higher-octane ‘Super’ grade to remain E5 to provide protection for owners of older vehicles.
Subject to parliamentary approval, the introduction of E10 at forecourts will occur during summer 2021 supported by a comprehensive communications campaign.
The initial legislation will apply to Great Britain only. In line with our obligations under the Northern Ireland Protocol, we’ll also notify the European Commission of our intention to legislate for the introduction of E10 in Northern Ireland to ensure regulations are in place before the September 2021 change in petrol grade.
UPDATE 11 July 2021. Mazda UK were asked for their position on use of E10 fuel in RX-8's and they quickly responded with an the official statement below. In summary, the important bit is, "E10 petrol is cleared for use in all models with petrol engines introduced in and from the year 2002".