Over the last few weeks 95 and 98 petrol have been the same price where I'm based. From what I've read 98 isn't worth paying extra for in a Prius, but now it's the same price. And 98 only has 5% ethanol vs 10% for 95. Any reason not to go with 98?
It's not made any difference in my car here in the States I usually use the sheets blue fuel and I can't remember how much ethanol is in it You can Google ...it's 88 octane. When I run regular 87 octane it doesn't seem to make any difference I've run some mid-grade and high test and never saw any difference in mileage in the Prius I guess because the engine is so choked up anyway no fuel is going to help it that's by design. So generally in the Prius I've just given in to running the most inexpensive gas that I can get which is usually the sheets blue '88 it's always cheaper than all the other gas so that's just what I run I've tried the others it made no difference no matter how fast I drive or what have you nothing dirt in the engine things like that The Prius already runs on its own vomit or puke so the engine is quite nasty internally as it's I guess just built that way It's EGR system and all that stuff this thing is regurgitating its own stuff all the time so why feed it steak when it's happy running on the cheapest hamburger .
The lower ethanol content blend should have a tiny bit higher energy content. But your engine won't know or care about the higher octane.