The codes you'll see on this site and at the pump — E10, E5, B7, B10, HVO — refer to how much renewable content is blended into the fuel, not the fuel's octane rating or "grade" in the way most drivers think of premium vs standard. Here's what each one actually means.
E10 and E5 (petrol)
The "E" number refers to the percentage of ethanol (a renewable, plant-based fuel) blended into the petrol. E10 contains up to 10% ethanol and has been the standard UK petrol grade since 2021, replacing the previous E5 standard. E5 (up to 5% ethanol) is still sold at most forecourts, usually labelled "Super" or "Premium," at a higher price — originally kept available because a small number of older vehicles (roughly those built before 2011) aren't compatible with E10. If your vehicle is compatible with E10, which the vast majority on the road today are, there's no performance reason to pay more for E5 — check compatibility on GOV.UK's E10 checker if you're unsure about an older vehicle.
B7 Standard and B7 Premium (diesel)
The "B" number works the same way for diesel, referring to the percentage of biodiesel blended in. B7 (up to 7% biodiesel) is the standard UK diesel grade and is compatible with virtually all diesel vehicles on the road. "B7 Premium" (sometimes marketed as higher-performance or additive-enhanced diesel) is still B7 in terms of biodiesel content — the "premium" label refers to additional detergent additives the retailer includes, not a different renewable blend, which is why this site tracks it separately from standard B7 pricing.
B10
B10 (up to 10% biodiesel) is a newer, less widely available diesel blend with a higher renewable content than B7. Not all older diesel vehicles are approved for B10 — check your vehicle handbook or manufacturer guidance before using it if you're unsure, since compatibility varies more than it does for B7.
HVO
HVO (Hydrotreated Vegetable Oil) is a renewable diesel alternative made from waste fats and vegetable oils rather than crude oil, chemically very similar to standard diesel and usable as a drop-in replacement in most diesel engines without modification. It's still relatively rare at UK forecourts and typically priced at a premium over standard B7 diesel, but is tracked on this site wherever a station reports it.