I understand that you would not want CD, and that caused you to cancel the purchase. However, I can't see why Mazda would want to advertise or promote CD as a selling point. Very few customers would have the slightest interest about an internal engine change that gives a tiny fuel savings, with no associated performance gain. Yes, the people on this thread do care a lot about such things, but the majority of buyers these days typically just consider their vehicle to be a travelling phone and audio system (and probably video for some as well). And that's what they want the automakers to tell them about.…. I canceled my purchase of a new 2018 CX-5 GT AWD when I learned Mazda featured the CD for 2018 CX-5 without any prior advertisements and announcements. ...
I certainly agree with you about CD, and would MUCH rather prefer that our vehicles did not have CD, or anything else that potentially decreases reliability and increases ownership cost. But as an owner who is stuck with it, the bottom line on this for me is how Mazda handles any future CD-related issues going forward. They apparently believed the ECM programming was the issue, and fairly quickly implemented a recall of quite a few 2018-19 vehicles, and also presumably did the same fix to the 2020's before they were sold. That the automaker took this step voluntarily and proactively is IMO a green check mark for them.
Now we certainly don't know yet if the computer programming change was a completely successful solution to the problem. And there won't be an answer to that question forthcoming until enough additional time passes, and subsequent CD issues either start showing up, or (hopefully) do not.
If significant additional engine problems do begin happening (CD or otherwise), then it will fall back on Mazda to do the right thing, and cover those issues with an extended warranty. Hopefully they have already diagnosed and evaluated this correctly, making any further action unnecessary. But if subsequent problems do happen, and they try to bail on their responsibility, then that's when they lose me as a customer.