Is 35 MPG at 56 MPH OK? (2.0 litre euro 6 engine)

Afternoon everyone. As the title suggests really........... We are just getting used to our new 3500kg motorhome.....single axle at the rear It is based on the new ford 2.0 Ecoblue euro 6 engine (130 bhp) It currently has 9000 miles on the clock. We recently did a trip up to scotland where for 99% of the time we stuck religiously at 56mph. There was no wind and the road was dry. Is an average of 35MPG over the course of 450 miles acceptable. I have the tyres pumped up to 55 PSI front and 65 PSI rear (IF I should be expecting more then as it is still under warranty then I will be able to take it back to the dealer to get them to investigate) Thanks in advance