Hi Lee530
I have a Tucson 2 litre diesel and it tows like nothing I ever had before and I often forget I'm towing till I look in the mirror.
Your Terror can should be even better than my tuc at towing -crikey thats why Hyundai built them and sold them and farmers all over thew world use them to tow everything from horseboxes to houses.
There is something wrong with your vehicle especially as it used so much fuel, my Tuc does 29mpg towing -Your trip of 440 miles using 140litres of diesel and returning 14.26 to the gallon is really crazy.
Where in the UK are you? Is there another dealer located nearby you could take it to-sounds like someone should check it out properly and even do an ecm check to ensure it has the right figures.
Go to
http://www.hyundaiownersclub.co.uk/index.php and put the details there as the admin guy -Tony may be able to assist as he is a Hyundai wizz.
Cheers Itza :460: :460: :460: