MPG...am I getting enough?
 

Hi

I recently bought a E320CDI Avantgarde state (39K miles, 2006 model)
With four up did a round trip of 70 miles, and returned 35 to the gallon.
As this involved some stopping and starting, country roads etc, I took it for a run along the A1 yesterday to see if I could improve on it. There were just two of us, 50+ miles at average speed of 50mph (mainly doing 70 on cruise control or using a light right foot. It returned 38.3 mpg. I was expecting better from this car as the hand book shows better figures, am I being unduly optimistic?
Love the car but do have it on one months Mercedes return no quibble deal if I want. (I would be loath to send it back but if there is any chance of getting better mpg from this car I want it!)
Any help, advice etc welcomed even if its bad news!
Cheers
Chris