Okay I think I'll stick with the High Octane, I get a couple or three more MPG too.

I filled up on the way to FITP with Tesco High octane and while driving up thought something was wrong with the car. Filled up on the way back with normal Shell (what I normally use) and the car felt more responsive, and slightly quicker. This could have been because the ecu was used to running on Shell mind...

Sainsburies = Shell
Tesco/Asda = Esso/BP (region specific)
Morrisons = Texaco

But so you all know, no matter who supplies the contract, whoever the name on the tanker, the actual petrol going into these tankers comes from exactly the same central based refinery in the UK, made to same standard (EN 228).

The only difference is the adatives they add to the fuel. The increase in ron is based on increased levels of methonol in the additive.

So, heres an argument starter - do you still think any one companys fuel is any better than any others? or is it mind over matter?

Some are better and its been tested and proven

you stick alcohol into your fuel your going to get a better bang, but that doesn't mean its "better"

Where do I get this alcohol from? Anything? Just a bit of good old Jackie D

TBH I just fill up whereevers cheapest, never had any problems, I don't think the vast majority of the population even worry about it, just go to the nearest pump

if your running on track days then i can see the need for hi octane fuels but for normal day to day running on an st, standard fuel is fine. i only put it in once every 4-5 fillups for a clean and thats only half a tank. dont care where it is from its just usually the cheapest i go to

I just use regualr shell all the time as its my nearest petrol garage and is normally cheaper than other places

I used to always use BP but they got to greedy and charged upto 5p more a litre than shell!

I always use the cheepest for everyday driving. When im going on a rolling road i run it down and use the good stuff for a week or so prior

Is that for the added 3-4 BHP that you supposedly get? Have you ever tested if you do actually get the added BHP?

I think you may get 1-2bhp if you're lucky!!

its only really in subaru's and that sort of performance car that benefit from it really. Think they did a test on fifth gear with it on normal cars then going upwards to more high performance orientated ones

Somebody earlier in this thread said that the 'basic' ecu on the Fiesta ST can't adapt to higher RON fuels. This is in correct, the engine management software for the ST includes active knock and will advance spark timing to a predetermined knock limit. Therefore if you put a higher RON fuel it will give you more spark and theoretically more power.

No that was Dave that said it....it can't adapt

correct it has adaptive tables that can repopulate accordingly, may not notice anything on the road but maybe on a rolling road, filled my half tank of VPower with standard on top other day and runs just fine on the mix