What car next!

Mercedes E350 estate 😉 

Thats one I had not thought off 

I have an 07 reg R320 It goes my Coachman Laser  with ease ..... just not the most economical of vehicles.... low 20s when towing.

I would be wary of noseweights on the Mitsubishi and the Volvo with your Swfit as some models are quite high and the cars lower than expected. 

Aside from this, I can recommend a Jeep Cherokee 2.0L Diesel.    We have had ours since February and it's been one of the best towcars we've had.    We had gone out looking for a Sante Fe or Sorento, but were completely blown away by the Jeep.  

Just swapped my Shogun last Christmas for Hyundai Santa Fe Wiggins edition never thought l could better the shogun but up to now the Santa Fe is winning hands down for towing ability, comfort, MPG and the amount of luggage space is unbelievable so much so nothing in the van only cloths water butt and waste master and those would fit if l dropped the back seats. At first when it was new MPG around 23, now its got 6500 thousand on the clock its up to 27 to 28 mpg on average. l think it may level out has more miles go on at around 30 mpg. A big difference from 18 to 20 mpg that l got from the Shogun. plus road tax 300 pound cheaper

jeep Cherokee KL 2l diesel auto. will pull anything. 32mpg towing and 46mpg motorway at 70 mph in cruise control. not the best looking car but I like to be different.

 Same here - great towcar.  Great solo as well as it is more like saloon car.  We get about same mpg as you.  

Shogun.

Tow an office block up a scree cliff face in a hurricane.

Heavy, solid, stable, reliable.

Your choices, the Hyundai and Volvo are well thought although I would also add the E class MB.