William,
I've got a Kia Sorento & yes you're quite right they only do it with a 2.5 turbo diesel (diesel option, there is a petrol engine available)its rumoured that the new 2010 model will have the 2.2 diesel engine.
Mines a manual pre face lift 05 0n a 55 plate. 03 models can be bought for a couple of grand, but as all things in life you get what you pay for, if you want one go for as late a model as you can afford. XE is the base model, XS is the next one up, folowwed by the XT & the Titan (the Titan is an XT with 18 inch wheels)
over the last 12,000 miles solo my fuel economy ranges between 35 & 41 mpg depending on how I drive it (super old fart mode gives the better economy), expect significantly less with an auto, 0ver 3,000 miles towing mpg ranges between 19 & 24 depending on load, inclines (hilly & mountainous regions) & wind direction (my Bailey Indiana is about aerodynamic as a brick & headwinds seriously affect the fuel consumption).
Having said all that I wouldn't change it for any other tow car, quite simply it's superb as a tow car, just come back from France & did over 1900 miles towing without a hiccup (car wise)& averaged 23.9mpg towing. No wonder it was the Caravan Club's tow car of the year for a couple of years running! and is constantly there at the top of the JD Power reliabilty & affordability (cost of ownership) surveys