Ford Flex.
The Flex has an optional Class III tow package that allows 4500#. I have run one (a FWD) down the highway on cruise and averaged 26 MPG (EPA highway rating is 24 for the FWD, 22 MPG for the AWD.) Tons of room inside, good wheelbase for towing stability. The tow package includes a engine
oil cooler and hitch reciever with both 7 pin and 4 pin connectors.