UK Fuel Type Comparison
The UK fuel market offers several options at the pump — standard E10 petrol, premium E5 petrol, diesel, and LPG. Each fuel type has different energy content, emissions characteristics and economy implications. This reference compares them side by side so you can make informed decisions. Note: actual pump prices are not included here as they change daily.
Fuel Types at UK Filling Stations
| Fuel Type | Octane / Cetane | Ethanol Content | Notes |
|---|---|---|---|
| E10 Petrol (standard) | 95 RON | Up to 10% | Default pump petrol since Sept 2021 |
| E5 Petrol (super/premium) | 97–99 RON | Up to 5% | Required for some pre-2011 cars |
| Diesel (DERV) | 51+ cetane | None (FAME biodiesel up to 7%) | Higher energy density than petrol |
| Premium Diesel | 55+ cetane | Varies | Added detergents, marginally better economy |
| LPG (Autogas) | 105–115 RON equivalent | None | Requires conversion kit; fewer filling stations |
Energy Content Per Litre
| Fuel | Energy (MJ/litre) | Energy (kWh/litre) | Relative to Petrol |
|---|---|---|---|
| E10 Petrol | 31.2 | 8.67 | Baseline |
| E5 Petrol | 32.0 | 8.89 | ~2.5% more |
| Diesel | 35.8 | 9.94 | ~15% more |
| LPG | 25.3 | 7.03 | ~19% less |
| Ethanol (E100) | 21.2 | 5.89 | ~32% less |
Diesel contains roughly 15% more energy per litre than petrol, which is one reason diesel engines tend to deliver better fuel economy in miles per gallon. However, diesel is typically more expensive per litre at the pump. LPG has less energy per litre but is significantly cheaper, which often makes it cost-effective despite the lower economy.
Typical Economy Differences
| Fuel Type | Typical MPG (combined) | Litres per 100 km | Notes |
|---|---|---|---|
| E10 Petrol (small car) | 45–55 | 5.1–6.3 | 1.0–1.5L engines |
| E10 Petrol (medium car) | 35–45 | 6.3–8.1 | 1.5–2.0L engines |
| Diesel (small car) | 55–70 | 4.0–5.1 | 1.4–1.6L diesel |
| Diesel (medium car) | 45–60 | 4.7–6.3 | 1.6–2.0L diesel |
| LPG (converted petrol) | 30–40 | 7.1–9.4 | ~15–20% worse than petrol by volume |
| E5 vs E10 difference | +1–2 mpg | — | E5 gives marginally better economy |
CO&sub2; Emissions by Fuel Type
| Fuel | CO&sub2; per litre burned (kg) | Typical g/km (medium car) | NOx Concern |
|---|---|---|---|
| E10 Petrol | 2.12 | 130–160 | Low |
| E5 Petrol | 2.19 | 128–155 | Low |
| Diesel | 2.68 | 115–145 | Higher (particulates + NOx) |
| LPG | 1.51 | 140–175 | Very low |
Diesel produces more CO&sub2; per litre burned but tends to produce fewer grams per kilometre because of better fuel economy. However, diesel engines produce higher levels of NOx and particulate matter, which is why many UK cities have introduced Clean Air Zones with diesel surcharges.
Related Calculators
- Fuel & Economy Calculators — calculate fuel costs, compare economy, and estimate journey costs
Energy content values are approximate and based on UK fuel specifications. Real-world fuel economy depends on driving style, conditions, vehicle age, and maintenance. CO&sub2; figures are tailpipe emissions only. Fuel prices are not shown as they change daily — check current pump prices at your local forecourt.