What 99 RON means
RON is an octane rating. Higher RON petrol resists knock better, which matters most for engines designed, calibrated or tuned to use higher-octane fuel. In UK public fuel data, premium petrol is commonly reported as Super unleaded E5 rather than a precise 97 or 99 RON product.
What GOV.UK says about E5 and E10
GOV.UK explains that standard grade petrol is E10 95 octane, while E5 remains available as the super grade at 97+ octane at many filling stations. If your vehicle is not compatible with E10, GOV.UK advises using E5 in the super grade.
Why Route & Fuel maps 97/99 RON carefully
Because the public feed often says E5 rather than the exact RON, Route & Fuel applies conservative retailer mapping rules for common premium products. If the app cannot determine the product reliably, it keeps the fuel label generic instead of pretending every E5 price is 99 RON.
When 99 RON may be worth the price
- Your handbook or fuel flap recommends high-octane petrol.
- Your car is tuned or mapped for 98/99 RON.
- The station is on-route and the price gap is small enough to justify it.
- You value the fuel product for reasons beyond the cheapest pence-per-litre result.