This is supposed to do a combined 67 miles per gallon or use a cobined 4.9 litres per 100kms according to the dealers. Anyone care to comment on this as being accurate. I bought one 2 months ago and the average fuel I'm using per the information on the dash is 6.5 litres per 100kms and I'm an average type driver. Big difference per what Volvo says the car can do and per what I'm doing ?