Try Jeep, they understand towing and their 4x4's that have a neutral in the drive link, are ready. They have a full time 12v plug in the console. Also, the cig lighter can be made hot full time by moving a fuse to a different position, check your manual. I have towed Wrangler, Grand Cherokee, and 2014 Cherokee.
Want mileage? The VW Passat Diesel gets 48 MPG and tows well on a dolly. You'll need short 2x6's to load or you can remove the front air dam. The plus, you'll get the mileage AND you'll have a real car. My old brake buddy works for all applications.
A hint, when going over 12 to 14K foot mountains and your Towed is over 3,500#, ( I-70 west of Denver), drive the Towed and use it as a scout car for problems and pull off places. The passage will be quicker and use less total fuel. .....empty water and sewer tanks help as well.
