I found, based on consumption and cost of the fuel, the best compromise was 95......
A post from a previous thread.....
"For what it is worth I tried them all (91, 95, 98) when I bought my D3 V6 about a year ago..... ran it on 91 (Regular), 95 (Premium), and 98 (Super Duper Premium??). Compared costs of fuel with fuel consumption etc.....
In the end, premium, 95, is the way to go. Extra cost of fuel is saved by improved fuel consumption, so it is actually cheaper to run on 95 than 91, despite 91 being cheaper by the litre. 98 Is considerably more expensive and no notable improvement in fuel consumption. Funny enough, after trying all this I read the manual and it recommends 95....."

