From Crude to Pump
Petrol is produced by refining crude oil. Crude oil — a mixture of hydrocarbons extracted from the ground — is separated into fractions by boiling point in a distillation column. Petrol (naphtha) fractions come off at 35–200°C. Further processing — reforming, isomerisation, alkylation — converts these fractions into high-octane petrol components and adds oxygenates (typically ethanol) to meet regulatory specifications.
The key international quality standard in Europe is EN 228 (automotive petrol), which sets minimum requirements for octane rating (min. 95 RON for regular), maximum sulphur content (10 mg/kg), maximum benzene (1%), and ethanol content (up to E10 — 10% by volume). In the US, the equivalent is ASTM D4814.
Octane Grading: RON vs AKI
Octane rating measures a fuel's resistance to premature ignition ("knock") in an engine. Higher octane means more resistance, allowing higher compression ratios and better performance in engines designed for it. Two main measurement systems are in use globally:
| System | Used in | Standard grades | Measurement method |
|---|---|---|---|
| RON (Research Octane Number) | Europe, Asia, Australia, most of world | 95, 98, 100 RON | ASTM D2699 |
| AKI (Anti-Knock Index) | US, Canada | Regular 87, Mid 89, Premium 91–93 | (RON+MON)/2 |
| MON (Motor Octane Number) | Industry/technical use | — | ASTM D2700 |
The critical point for international comparisons: US 87 AKI ≠ European 87 RON. AKI is typically 4–6 numbers lower than RON for the same fuel. US Regular 87 AKI is roughly equivalent to 91–92 RON in European terms. Our detailed entries on octane rating, RON and AKI, and AKI explain the measurement systems in full.
Why Pump Prices Differ So Widely
The pre-tax wholesale price of petrol tracks crude oil benchmarks (mainly Brent crude) plus the refining margin (see our crack spread glossary entry). This component is broadly similar across markets. The enormous pump price variation between countries comes from:
- Excise duty: A fixed tax per litre, varying from near-zero in some Gulf states to €0.70+/litre in the UK and Netherlands. See our excise duty entry.
- Carbon tax: Explicitly proportional to CO₂ content — €0.27/litre in Sweden at their €117/tonne carbon tax rate. See our carbon tax entry.
- VAT: Applied as a percentage on top of all other costs. At 20% VAT, a €0.10 excise increase raises pump prices by €0.12. See our VAT on fuel entry.
- Subsidies: Some governments keep prices below cost — Iran, Venezuela, Libya, and several Gulf states. Our fuel subsidy entry covers the mechanics.
- Exchange rates: Petrol is priced globally in USD; a weaker local currency raises import costs proportionally.
The EU weekly oil bulletin breaks down EU pump prices into their components weekly. For a guided walk through the full price stack, see our guide on what makes up the price at the pump.
Ethanol Blends: E5, E10, E85
Most petrol sold today contains some ethanol — a biofuel that reduces net CO₂ emissions and boosts octane. The percentage varies by country and policy:
- E5: Up to 5% ethanol. Was European standard until ~2021 in most countries.
- E10: Up to 10% ethanol. Now standard in most of Europe, the US, Australia. Mandated in the UK from September 2021.
- E22–E27: India mandates 20% ethanol by 2025 as part of its ethanol blending programme.
- E85: Up to 85% ethanol. Used in flex-fuel vehicles, mainly in Brazil and the US Corn Belt. See our E10 and E85 entry.
The IEA transport biofuels tracking and ICCT biofuels analysis provide global policy context.
Petrol remains the dominant transport fuel globally, but its share is declining. The IEA Global EV Outlook 2024 projects EV sales displacing over 6 million barrels/day of oil demand by 2030. EU member states must end sales of new petrol and diesel cars by 2035 under Regulation 2023/851. The transition affects both petrol demand and — through reduced fuel tax revenues — how road infrastructure will be financed in coming decades.
Frequently Asked Questions
What is the difference between petrol and gasoline?
The same fuel — "petrol" in British English and most Commonwealth countries; "gasoline" or "gas" in North America. Composition and grading are equivalent, though octane measurement systems differ: RON (Research Octane Number) outside North America, AKI (Anti-Knock Index) in the US/Canada. See our RON and AKI entry for conversion.
What do the octane numbers on the pump mean?
Octane numbers measure resistance to engine knock. European pumps show RON (95 and 98 typical); US pumps show AKI (87, 89, 91–93). US 87 AKI ≈ 91–92 RON — not the same as European 87 RON. Full explanation in our octane rating and AKI entries. The ASTM D2699 standard governs the RON test method.
Why is petrol so much cheaper in the US than in Europe?
Pre-tax wholesale prices are similar. The difference is taxes: US federal gas tax is USD 0.049/litre while European excise averages €0.50–0.65/litre, plus 20–25% VAT. Taxes account for ~60% of European pump prices vs ~12% in the US. See US EIA gasoline price breakdown and EU oil bulletin.
What is E10 petrol?
Petrol containing up to 10% ethanol. Standard in most of Europe and the US since the 2010s. Fuel economy drops ~2–3% due to ethanol's lower energy density. UK government E10 guidance and our E10 and E85 glossary entry have compatibility information.