Embarrassed to say I deliberately tried to see how many miles I could get out of a 38 mile trip in the R with a mixture of motorway and round the houses.
It was at 44.3 but by the time I got my phone out and took the picture it had dropped slightly.
I recon I could have got more if I had put it into Eco mode and used the freewheel feature on a couple of small hills I went down.
Not bad for a car that has so much power on tap.