There's no benefit on using 99RON fuel in our engines
All unleaded is the same but the additive package added by specific brands makes the difference.
I just add a 50ml shot of Miller Petrol Ecomax which should bring any supermarket fuel up to Shell Wallet Cleanser standard.
Have been lucky since getting the CHR as have used Sainsbury's fuel vouchers meaning I've paid no more than £1.06ppl, when doing so I always take 5 x 10l jerry cans so I can use the full 100l allowance. Also means that in 1800 miles driven I've only been to refuel at a station twice so far.
So how much are you paying per liter for your fuel?