Well............... normally a diesel takes ages to run in properly and give its best fuel consumption. 10k maybe? My MPG figure yesterday was along the M4 to West Wales @ 75, then onto the A roads at 60-70 ish, a bit of around town work and then head home. 51.5mpg was the average on the computer. Today I "only" got 49.2mpg but then it was running for 10mins deicing at the start of the day and then 45mins of stop start traffic coming through Bristol tonight. I've done just over 300miles on this tank and it says i've got 230 left
My old car struggled to get 230 out of a full tank when driven slowly, and that was also a 45ltr tank.