I was given a CX-5 diesel as a loaner today when they serviced my Reserve (I guess they had to find some use for it), so I drove it around town for a while and took it out on the interstate.
The things I immediately noticed were the roughness of it (not quite as smooth driving as my Reserve) and the acceleration...it was fine, but it was different. You could really tell that the transmission is geared differently. But it moved on the interstate when I put my foot into it.
The computer mileage for its 1,000 miles was 27, I assume mostly around town. That's not spectacular, but my Reserve only gets 19 until it warms up, and that takes 10 miles or so. After 8,000 miles my computer mileage is under 24.
Getting back into my Reserve, I could tell how much quieter and smoother a ride it is. The difference is stark.