I've not towed with the more recent petrol engines being a diesel man, but personally I would expect that the l/100km will be similar to the Ford. With similar power & torque outputs I don't think you'll be seeing any real advantages or differences. Yes the smaller engine will use less fuel, but you'll have to work it harder.

You'll be towing at about 83% of the tractor weight (X5 weighs in at around 2100kgs depending upon gearbox option) and with an engine with 114,000km on it will probably be asking a lot of it. The engine & transmission will be slack and if manual you'll probably be looking at clutch issues too. Nose weight limit on the OEM tow bracket is lower at 120kgs so a bit of load re-balancing will be needed too.

As a tractor, the post 2004 diesel auto will be a much better option but is unfortunately out of your price range at present. We don't have additional cooling on the UK models as it's too blasted cold here anyway. You might well need it out in Oz though.

I agree that although a BMW will be a much better vehicle than the Ford in all other respects, the differences for towing performance are probably marginal.

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