Sticking to the A roads of Herefordshire, and the speed at which other people drive, I can easily see 37-40mpg on a nice warm day (over 20 miles). If I hoon it around I get low 30's - short town journeys high 20's.
I tend to find the mpg on the MKV on the trip computer is not the best - for instance I've seen the average since fill be 37mpg and had nearly 400 miles until the petrol light comes on. On another occasion I've had 35mpg and the light come on at 320miles. I always reset my overall trip when filling up.