Hi,
I can tell that the Echo and the xA are very similar:
I had to take it off for the winter -- too much stuff would have gotten stuck up on top. Do you have pictures of the front grill area? I have found that sealing up and smoothing the nose of the car is at least 2X more effective than mods on any of the other areas of the aerodynamics.
http://ecomodder.com/forum/showthrea...mods-2969.html
I tried covering the holes in the radiator cowling, between the bumper and the radiator, and I found that it added drag -- though I think if you close down the front grills enough, you can see some big improvements. (See the latest grill block at the end of the thread.)
I think the Echo has one big advantage over the xA: the wheel openings are much tighter to the tires, I think.