Motorists in the UK can now fill up with a cleaner form of petrol - E10, which is made with up to 10% bioethanol - will be the standard offering at forecourts as part of British government's plans to cut carbon emissions.
It is replacing E5 petrol, blended with up to 5% bioethanol.
E10 is also due to arrive in Northern Ireland in early 2022.
The UK's Department for Transport said more than 95% of petrol cars licensed for use on Britain's roads are compatible with E10, which is not expected to cost more than E5.
A January 2020 impact assessment estimated that around 600,000 cars - such as classic cars or those built in the early 2000s - would be incompatible with the new fuel.
Owners of those vehicles can continue to access E5 by purchasing super unleaded which costs an average of 8.7p a litre more than standard petrol, according to AA figures.
The department admitted that E10 can "marginally" reduce fuel economy but it insisted the impact is "almost unnoticeable to most drivers when making every day journeys".
It stated that the rollout of E10 could cut transport CO2 emissions by 750,000 tonnes per year which is the equivalent of taking 350,000 cars off of UK roads.
Transport minister Grant Shapps said: "Every journey matters as we drive forward the green industrial revolution, which is why the rollout of E10 is so important.
"It'll help us cut road greenhouse gas emissions and meet our ambitious net zero targets."
In a survey of 1,450 UK drivers by the RAC, which provides breakdown assistance and other motoring services, suggested that 27% of motorists are yet to check whether their car is compatible with the new fuel.
AA president Edmund King said: "This is a positive and simple step to help reduce the carbon impact from road transport.
"While the vast majority of vehicles will be unaffected by the change, it is important for owners of older cars to use the government's vehicle checker to see if they can use E10.
"Even if E10 is put in a non-compliant vehicle, drivers should not panic and can simply put super unleaded in their tank at the next available opportunity."