Shell V-Power
 

Today I bought Shell V-Power, to see if it makes any difference to the car's performance and, ultimately, fuel efficiency.
I normally use Supermarket Regular, but last top up I used Supermarket Premium and my car felt a bit "snappier".
However, after today's top up, I think I will revert back to the Supermarket Regular. The prices are out of all proportion.
Shell V-Power is $6.33/US gallon.
Supermarket Regular is $5.55/US gallon.

It wasn't too long ago that Shell was advertising their new additive package. I'm sure it's good fuel, but it's probably not all that much different from other "top tier" brands.

Something to be aware of, higher octane fuel actually has (slightly) less energy per volume than lower octane fuels. On the one hand, some engines may add timing due to increased resistance to knock, but on the other, there's physically less energy released.

In the US, gasoline from various brands usually comes from the same distribution point, with differences in the detergent packages that are added in. The gasoline itself is very uniform, but the cleaning agents vary. The government sets a minimum detergent level, and TopTier certified fuels have an even higher minimum.

As Ecky points out, higher octane fuel has slightly less energy, so only use it if your engine calls for it.

Last fill up I moved up from my usual 95 RON to 97 RON and I found the car ran slightly better. My FE improved slightly, but not enough to say it was the petrol as against just variance. I went for the V-Power this time (last time was supermarket Premium) because of the improved additives, but at the price I don't think I will bother in future.

Unless the engine is turbocharged, there are only two times you SHOULD consider using a higher octane petrol:

1) when traveling heavily loaded in mountainous areas and/or...

2) when the petrol along the route (or at destination) are KNOWN to be of lower quality than what you normally use. Effectively, you're mixing Hi+Lo to get average normal octane.

i use 98 RON in my car, and it consumes 6% less of it than 95E10, 95 Ron with 10% ethanol.
98 RON is 4,24 % more expensive than 95e10. But it depends on the car

My Acura manual says to run 91 PON, but in the US, the grades are typically 87, 89, and 92. Sometimes I'll manually mix regular and premium to get close to the recommendation, but usually I run regular 87.

I can just barely tell the difference between 87 and 92 in the Acura when driving under heavy engine load. There is no discernable MPG difference, but the timing advances slightly more readily with 92.

So, in the Acura, which is designed for higher octane fuel, it barely makes a noticeable difference. Cars designed to run on regular octane probably will not notice any difference.

JockoT- What octane does Honda say to run?

Finally, higher elevations can get away with lower octane fuels since they have lower effective compression. This is why mountainous areas in the US run 85 PON for "regular".

RedPoint5 - Just be aware USA and Europe octane numbers are calculated differently.

Yeah, which is why I listed PON. I'm not sure how it converts, but figured I'd give my experience with the PON system.

It would be no surprise at all if even a random econobox with a low-compression engine could experiment some slight fuel-efficiency improvement with a higher-octane gas, since it would enable a leaner burn.