Would my ST-3 run better on higher octane fuel than 91, if so can you notice the difference as the price for higher octane fuel is quite a lot.

Son has a ST1 and he only puts in Tesco Momentum now, he's had the car for a year and at first he was banging in bog standard unleaded, but then a friend of his who rallies cars advised him to use the Momentum fuel as it'll do more miles per gallon and will run smoother & faster, the car using Momentum is a vast improvement over unleaded petrol.

 

A higher octane fuel will only be of any benefit if you are driving hard enough for the knock sensor to be compensating for pre ignition of the fuel.

For normal driving it will make no difference.

Other additives in some fuels eg. cleaning/ frictions reducers etc.. may be of some benefit but I'm not convinced they are worth the extra cost of the fuel.

I did experiment with a few tankfuls of Shell V power in my 2016 ST-Line Fiesta  but noticed only a marginal improvement of about 1.5mpg but that was outweighed by the cost.

 

I’ve always stuck to what the manufacturer recommends. If an engine has been designed to run on a given octane rating, it’s more than adequate for the compression in the engine. I’d put in a higher octane if the engine was a higher compression but even in an ST Fiesta, I don’t think it’s necessary. 
 

I see why higher octane fuel is used in rallies, but again, all depends on the car being rallied. For normal driving, even if someone feels a difference, I’ve never thought the large difference in price was worth it. Especially as sometimes the difference can be 15-20p a litre and on a 40 litre tank for a car that doesn’t really need it and isn’t being driven heavily like in a rally etc, to me it’s just a waste of around £8 a tank

Here in Egypt we only have RON 92 and RON 95 , I use 95 , a friend of mine who has the same car , fiesta ecoboost 1.0 100ps automatic, uses 92 with only marginal difference in fuel economy and performance, but I believe that if you do spirited driving, or other severe duty usage such as going up hills with full load or towing a trailer, then minimum RON 95 would be a must 🙂 

Can't really see the point of paying all that extra per litre for what is in fact a road car.

On 1/4/2020 at 5:40 PM, Gallego1968 said:

Would my ST-3 run better on higher octane fuel than 91, if so can you notice the difference as the price for higher octane fuel is quite a lot.

Are you really using 91? Thought the lowest in the uk was 95. If you are then you probably would see a difference, think 95 is recommended by ford as the lowest used.

2 hours ago, Bobr said:

Can't really see the point of paying all that extra per litre for what is in fact a road car.

I think the same Bob but like me Son he feels he needs to put in that Momentum.

Can you remember Five Star fuel ? By christ what stuff that was in my RS2000, like it was turbo charged.