When you fill up with petrol, you may wonder whether to choose Eurosuper 95 (unleaded 95) or Eurosuper 100. The two differ in octane rating, which affects engine performance, efficiency and price. Understanding these differences helps you make the best choice for your vehicle.
What is the octane rating?
The octane rating measures a fuel’s ability to prevent engine ‘knocking’ during combustion. Knocking happens when fuel burns unevenly, causing vibrations and potential engine damage.
- Eurosuper 95: has an octane rating of 95. It is suitable for most standard engines and delivers reliable performance under normal conditions.
- Eurosuper 100: has a higher octane rating of 100. It prevents knocking better, making it ideal for engines with higher compression ratios or turbochargers.
Performance comparison
- Engine compatibility:
- Eurosuper 95: designed for cars whose engines don’t require high-octane fuel. These are usually city cars, hatchbacks and saloons.
- Eurosuper 100: recommended for high-performance engines, such as sports cars or luxury models, that benefit from high-octane fuel.
- Power and smoothness:
- Eurosuper 100 can improve power, acceleration and smoothness in vehicles optimised for high-octane fuel.
- In cars designed for Eurosuper 95, switching to Eurosuper 100 won’t bring any noticeable benefits.
- Heat resistance:
- Eurosuper 100 copes better with higher combustion temperatures, which is key for turbocharged engines or vehicles used in demanding conditions.
Efficiency and maintenance
- Fuel efficiency:
- High-performance engines running on Eurosuper 100 may achieve a slight improvement in efficiency thanks to optimised combustion.
- Standard engines running on Eurosuper 95 are already efficient and gain little from higher-octane fuel.
- Engine health:
- Using Eurosuper 100 in vehicles that need a high octane rating prevents knocking and reduces the risk of engine wear.
- Regularly using the right fuel, as recommended by the manufacturer, prevents deposits and ensures a long engine life.
Price differences
Eurosuper 100 is more expensive than Eurosuper 95 because it undergoes extra processing to achieve the higher octane rating. Drivers of standard cars who want to save can choose Eurosuper 95, as it offers excellent performance at a lower price. For high-performance vehicles, however, the extra cost of Eurosuper 100 is justified to protect the engine and maintain performance. You can compare current prices for both fuels on our fuel prices page.
Should you switch to a higher octane rating?
- Stick with Eurosuper 95 if: your vehicle handbook recommends 95-octane fuel and your car is a standard model. Switching to Eurosuper 100 won’t bring extra benefits and will cost more.
- Switch to Eurosuper 100 if: your vehicle is tuned for high-octane fuel or has a turbocharger or high-compression engine. Also consider switching if you hear engine knocking or the car runs poorly on Eurosuper 95.
Octane myths
- ‘A higher octane rating means more power for any car’
Not true. Higher-octane fuels only benefit engines designed for them. Using Eurosuper 100 in a standard engine won’t increase power or efficiency. - ‘Eurosuper 95 damages high-performance engines’
Although it won’t cause immediate damage, long-term use of lower-octane fuel in high-performance engines can shorten engine life. - ‘Switching fuels often damages the car’
Switching between Eurosuper 95 and 100 doesn’t harm the engine, as long as the fuel meets the manufacturer’s minimum requirements.
Conclusion
Choosing the right fuel depends on your vehicle’s design and your driving needs. Eurosuper 95 is perfect for everyday cars, offering a balance of price and reliability. Eurosuper 100 is key for high-performance engines because it ensures smoother running and better protection in demanding conditions.
Always check your vehicle handbook for the recommended octane rating, and consult a trusted mechanic if you’re unsure about switching fuels.