The latest 171bhp xtrail weighs in around 1720kg, 85%=1462kg.
I have only towed with it once, the the computer was showing 33.4mpg, towing 1333kg.
Again solo the computer shows 40/44 mpg.
Someone with the same model on this site checked the computer with the brim to brim method, he found the computer was 2mpg optomistic.
Still i am amazed at the economy.
My previous 2.2 134bhp xtrail, was just as good a tow car, weighed around 1650kg.(85%=1402kg)
But solo gave high 30's, towing around 30mpg, which again i was happy with.
Obviously towing 1490kg will drop the mpg figures.