I'm getting close to 400 miles, but I hasten to add, thats using 32 litres, that costs about £30ish @ 94.9p a gallon of diesel... That was with my first 2 tanks, both of which I got 60-62 mpg per tank..
On the Dooper the fill-up sign comes up with 8 litres left!
Never had a diesel before, and was advised that whatever you do don't run out, its different to a petrol... It won't just start up by getting some more diesel in a can from the nearest garage...
So I don't get obsessed I've not checked the gauge for a while and even with occasional spirited driving, i.e flat out, I'm still getting 55mpg!. But I think the secret is, is that when you aren't accelerating just get used to peppering the accelerator on downhill parts of a journey.
Speaking to others who have had diesels from new they reckon mpg improves after a few months by a 'bit'..
I bet the new 08 Dooper will prob get about 5 mpg more than the 07 model in the real world..