RON 97 vs RON 99: which petrol should you use?
Compare premium petrol labels, price and route fit before choosing a super unleaded stop.
Higher RON can matter when the engine is built or tuned for it.
RON is an octane rating. Higher RON petrol resists knock better, which matters for some high-performance, high-compression or tuned engines. If your handbook or tuner specifies 98 or 99 RON, do not treat a cheaper lower-RON product as the same thing.
Route & Fuel shows 97/99 RON labels for common retailers and keeps the app label generic when the fuel cannot be determined reliably.
Check the car first, then compare the price.
For fuel choice, your owner’s manual and fuel flap label matter more than a generic website recommendation. If your car asks for a minimum RON, use that or higher.
| Fuel / label | What it usually means in the UK | Who should care |
|---|---|---|
| E10 petrol | Standard 95 RON petrol with up to 10% renewable ethanol. | Most modern petrol cars, unless the vehicle is not E10 compatible. |
| Super unleaded E5 | Higher-octane petrol, generally 97 RON or higher, with up to 5% ethanol. | Older E10-incompatible cars, some performance cars, tuned cars and drivers whose handbook asks for higher octane. |
| 97 / 99 RON | RON is the octane rating. Higher RON resists knock better in engines designed or tuned to use it. | Cars that require or recommend high-octane fuel; benefits in ordinary engines are usually limited. |
Do not chase the wrong premium pump.
For premium petrol, the cheapest E5 price is only useful when the RON label, detour, route position and fill size all make sense. The app helps compare those factors before you choose a stop.