OK, 2nd tankful measured brim-to-brim. 39 mpg; computer indicates 30mpg. Is the poor fuel consumption a fallacy?
The tank was refilled at 3/4 full with 408 miles recorded. Last fill up was after 542 miles and the warning light was on.
Sorry Fraser but refilling at 3/4 full, could make a difference of 2/3 gallons in the calculation.
The only way to due a true calculation is to fill the car to the brim, then drive it as far as you dare, then fill up to the brim. I have run my Brera until there was only 2 litres of fuel left in it (put in 68L, tank holds 70L), that way I can get a very accurate figure for mpg, and found the computer is pretty accurate.
With your calc of 39 and the computer saying 30 I would back the computer, I don't think it would be 25% out, also if you read the posts most owners are getting low 30's out of the 2.4.
The 2.4 might feel it has more punch, but in the 0-60 game there's nothing in it against the 2.2, also the 2.2 hasn't got the extra weight at the front so it may handle better, and on top of that the problems of Breras wearing the inside of the front tyres appears to be applicable more to the 2.4's.
Basically if you want an engine that you can tune up for relatively little money get the 2.4 diesel, if you are looking at the 2.4 from purely an economy perpective imho forget it, not for an additional 3k premium and then cam belt changes on top.
Sorry Fraser, I've owned diesels in the past, so I'm not against them but most people choose a diesel for economy v cost to buy, unfortunatly the 2.4 doesn't deliver.