my petrol one was loosing water from cracks in the expansion bottle. Put a new un on n that cured it. The cracks were under the yellow stiker around the lid. Have a look at yours.
seems poor, my petrol averages 340 miles on a tank, mainly motorway tho. averages bout 27 to gallon in winter n 32 to gallon in summer. the auto box won't be helping you.
Got a freelander 1.8. was losing water but no signs. read loads on landy zone bout head gaskets and thought the worse. read one thread that said try the expansion bottle. Did that and now sorted! cheers. and of course, fingers crossed!:)