Super unleaded - is it worth the extra cost?

[RWD cossie wil]

tali1 said:

Used Shell V Power - made fk all difference (which was what i was expecting anyway)-in fact MPG slightly DROPPED!
Rule of thumb is any %improvement in MPG must be better than extra% price of Super

What car were you driving?

[TomS09]

Got no choice in my Accord Type-R which is minimum 98, so usually put tesco 99 in dont want to even try 95. To be honest as fuel keeps rising the 5p or so difference is not going to look very much soon anyway!

[CDP]

It depends on what the engine's designed for. If they say 95 RON then you are probably chucking money away. The main gain of a higher octane rating is the ability to run a higher compression ratio or boost in the case of a turbo. Modern ECUs can often take this into account but it could be the lower spec models will ignore it in software to make you buy the high output version.

When I got my race engine built for my Locost, Alan at Scholar said super unleaded would be a complete waste of money at the compression ratio allowed in the regulations. As they've been building FF engines for 40 years they must have tried pretty much everything so would certainly jump on an easy power gain. This doesn't stop the other competitors using it of course.

[Steameh]

I use 95 in my car.

[Switch`]

I get 220 miles out of a tank on 99+
and 200 miles on 95~

[tali1]

RWD cossie wil said:

tali1 said:

Used Shell V Power - made fk all difference (which was what i was expecting anyway)-in fact MPG slightly DROPPED!
Rule of thumb is any %improvement in MPG must be better than extra% price of Super

What car were you driving?

Rover 75 2.5

[Chicane-UK]

My car has been remapped to use 97+ - so a definite yes for me! Won't run right apparently on 95RON though I haven't tried it...

[RobCrezz]

DJC said:

Then you lot must drive an awful lot differently to me.

In everything from an Mx5, MG, Integrale, Griff and Sag Ive never found *any* difference during my normal driving whether I used 95 or Optimaxy type stuff.

Mpg stayed roughly the same, performance stayed roughly the same. Reliability stayed the same.

And *my* S6 was still strong after 20k and as everyone in the entire possible world knows, that is the most fragile and dodgy engine in the world ever!

Its not about driving differently, its about different engines. The ones you listed, it is totally believable that it made no difference, but with many engines it does, fact.

[Matt_N]

I too have a prefacelift ATR which requires 98RON.

My local station is Sainsbury's but their SUL is only 97RON and I swear the car feels less perky on that than V-Power.

I try to get V-Power when I can.

[aizvara]

The topic has been done to death, but I'll add that when I got my e46 325i, it was filled with normal unleaded for the first few tanks. Out of interest I tried BP Ultimate, and noticed that the engine and car ran more smoothly after a few miles. The manual recommends higher octane fuel, too.

I haven't noticed any real power gains; possibly some efficiency gains, but for me its worth it simply to have a nicer sounding car.

[FamilyDub]

Smart ECU's and cars optimised to use high octane fuel will run better on higher octane fuels.

Subjectively, my car (MKV GTI) 'feels' better using SUL, which is set-up to want 98 RON +.

However, spreadsheets don't lie... I did about 4k using 95 when I bought the car (~24 mpg) last winter and about the same sample mileage this winter and I'm seeing about 3.5mpg more using 99 RON fuel.