Garry, the RX D40 will be a better tow rig, as the D22 is a detuned 2.5lt, so you going to missing out on a lot off KW and Torque.... Also if you going to be driving it on a daily basis, the D40 is more comfortable...
Economy is the same similar for both...
As you know, auto is a delight to tow with, D40 get the auto, the D22 doesn't