Super unleaded - is it worth the extra cost?
Discussion
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.
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.
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.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!
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.
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.
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.
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.
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