Normal Unleaded or Super Unleaded?

[Dblock]

Wondering the same thing, I thought I'd do as scientific test as I could muster.

 

I logged my fuel consumption to work (13.6miles) 10 times on Tesco 95, and after a few tanks of Tesco 99 I logged 10 journeys on that fuel too. (this journey is mostly dual carriageway so predominantly constant speed and throttle).

 

Tesco 95 Results:

 

Average speed of 10 journeys: 51.16mph

Average fuel consumption of 10 journeys: 32.9mpg

 

Tesco 99 Results:

 

Average speed of 10 journeys: 51.13mph

Average fuel consumption of 10 journeys: 32.6mpg

 

So you can see that on a very good statistical sample, the difference is within experimental error. From this I would also infer that there is no (or little) power improvement. Any difference between fuels is not great enough for the ECU to significantly adjust ignition timing and run more efficiently, so power is also unlikely to increase. I'd be interested in anyone who's done faithful back-to-back rolling road tests and compared fuels, although rolling road tests obviously come with a pinch of salt.

 

Well really you need to do alot more than 10 journeys. How long is the trip? wind speed has alot to do with it, other cars and so on.

 

Also you should try trips where acceleration is required e.g. town driving or stop start.

 

Im not sure about everyone else's car but if im tootling around the zed seems to get slower. When I floor it take a a few runs for it gain power. Im sure Abbey and Rstuning find the same on the dyno.