MPG 2.8JTD Chip
Van, Knaus Sun Traveller, Fiat Ducato, manual 2.8 JTD, not exactly steamlined.
I did an extensive journey down to Spain from Northern Scotland this spring. Fuel consumption varied considerably dependant on conditions. On a good rural road in flatish country the best I got was 10.1 L/100km (28mpg) at a steady 90 kph.(56 mph)
The worst, in the black mountains was 14 L / 100 km (20 mpg)
I have taken the plunge and fitted a chip to the fuel system by "Chip Express".
Recently done the West Highlands and returned 11.5 L / 100 km (25 mpg), that's pretty hilly but not as severe as the French mountains. Due to lack of Aires I was carrying a full water tank, on the refill when you can principle.
At the end of this month I am going down to Portugal so will then get a better average consumption figure. Will report further.
What is immediately noticable is a significant improvement in torque and a much wider power band, possible to get down to 1500 rpm in 5th with no apparent stress or discomfort. Overtaking is now an option !!
So, so far, so good.
I have decided that I don't really like front wheel drive, mainly due to lack of grip on loose surfaces at low speed. More than once I have had to reverse out, throwing the weight onto the driven wheels. ( Some Mercedes come with a diff lock, but not a chance with a Fiat)
As for the automatic question, I personally am much happier having more control over the ratio in use and engine rpm. I'm not familiar with the 3 litre Fiat engine, but imagine that it will not be disimilar to the 2.8, but with a more modern fuel control system.
BTW, what convinced me to buy the Knaus was that I could stand up inside and draw the curtains on the bed and drive away.