what type of fuel

[v8kev]

is there any substantial proof that shell vpower or bp optimax or any other is better or best for the car/engine for the extra cost

[finestjammy]

In word, no. It does seem to produce more pops and bangs and hopefully keeps everything nice and clean and lubed. It will also help protect against pinking, just don't expect an increase in bhp.

Edit: must read properly, you didn't ask if it increased bhp, so yes it is supposed to be a cleaner fuel, not sure what 'evidence' there is though.

[tonys]

Assuming you mean superunleaded, I haven't noticed any difference when using other brands (Shell few and far between where I am).

Other won't entertain anything other than V-Power or BP, although it might be down to the individual engines and other vagaries they've undergone over the years.