F type V6S motorway MPG

[Waitey]

Evening all,

I'm just looking into the viability of the V6S being my daily.

I currently do 90 miles a day of which 85 are on the M1 at a steady 70ish.

So at these speeds what does an V6S return? I know cost shouldn't come into it for these cars but when you are doing 18000miles commuting a year it all adds up!