The short answer
For most ordinary cars, no. It is worth it only where the manufacturer specifies a higher octane, which is generally performance and some turbocharged engines.
- Check the manual or the fuel flap. If it specifies 95 RON, that is what the engine is mapped for and higher octane gains nothing.
- If it specifies 98 RON, using 95 can cause the engine to retard its timing, which loses power and economy.
- Cleaning additives in premium fuels are real but modest, and an occasional tank makes more sense than a permanent premium.
- The price difference is significant, often more than ten per cent, which is a large amount to spend on a benefit you cannot measure.
What will ruin it
Putting petrol in a diesel car, or the reverse, is a serious and expensive error. Do not start the engine. Turning the key is what turns a drain-and-flush into a fuel system replacement.
Why it works
Octane rating measures resistance to pre-ignition, not energy content. A higher number is not better fuel, it is different fuel, and it only helps an engine designed to take advantage of it.
Tipking is general household information, not professional advice. Test anything on a hidden patch first. Full disclaimer.