better performance

[s4bandit]

hi guys
ive been using super unleaded from bp ( 97 ron ) since i got my car 4 months ago and last week i used somerfield petrol instead. again it is a super unleaded but doesn't have a rating on the pump to tell you the ron.
im not sure if this is the reason ( cant think of anything else ) but the car is now performing so much better.
so much so that i can't believe it, its like its been remapped or summit !
has anyone else try'd somerfields petrol or had a strange increase in power
for no reason ?
i'm gonna try using bp again to see what happens....
p.s. ive used tesco 99 aswell and that was the same as the bp

[kaisersolsay]

Never tried Somerfie;d.....dont have any petrol stations this side of the border I think?? I defo think that my B6 S4 runs so much better on 99 ron whetre it be Tesco or Shell.

[Pete.S]

I'm no expert on this, but I've read plenty of times before that from one tank refill of a different grade you will not notice any difference, as the timing has to adjust to the different grade over quite a time. Was the difference in performance recent, ie since it's got markedly colder over the last week? Could simply be that, causing air density to increase; I know that definitely helps the performance of turbo charged cars, not so sure of the effects of denser air on N/A cars though?

[s4bandit]

yep, it was recent, since the cold weather started, but it is such a noticeable difference that wouldn't everybody be noticing the same thing as me if that was the case ?
could it have anything to do with oil ? i have recently put the new magnetex oil in, cost a fortune !

[P_G]

Could be several factors, however the two more likely are yes the fuel and the fact that certainly in northern parts there has been a sharp drop in air temperature, certainly in the morning, Colder, denser air tends to aid the cars performance, felt the benefit in performance and exhaust note / sound in my old S4 and currently in the RS.

[kaisersolsay]

Anyone tried BP102 yet? Theres a BP station just outside of Edinburgh (South Queensferry) that now stocks it. I wondered if the 102 ron made much of a difference for the £2.42/litre!!