Without a standard, meaningful comparisons can be elusive. CR also limited their testing to “Performance” tires. Is there a standard for that?
Interestingly, they included the Michelin Cross Climate 2 in the test. This is a tire that some members of this forum are using. If I recall, it is one of the tires that has reportedly reduced efficiency compared to in the OEM tires. Looking at the chart from the CR testing procedure, we see the Nexus tire at 9.1 and the Michelin tire at 11.1. There is one tire that is a bit of an outlier which comes in at 12.8. The chart also shows the range of 9.1 to 12.8, corresponds to 29mpg and 28mpg respectively. This would put the Michelin tire very close to the middle, or 28.5mpg. That would make the Nexus 5000 approximately 2% more efficient than the Michelin CC2. The CC2, however, may be 8-10% less efficient than the Energy Saver A/S, which theoretically would make the Nexus tire 6-8% less efficient than the OEM tire.
A couple of things we don’t know are the weight of the test vehicle or the tire size used for the testing. Both factors could produce different results than if the test vehicle weighed 4000lbs and was equipped with 235/45-R18 tires. It’s a half baked report, which is why I put little value on the results.
I just put a set of Michelin Cross Climate 2 (19") on my wife's Tesla Model 3, and so far it seems to be an improvement on the OEM Continentals: smoother ride, less noise, and a much longer projected life.
If all you care about is rolling resistance, this would not be your top choice, but I plan to put a set on my Model Y when the stock Michelins wear out.
I'll reserve my comments about CR, but I do want to endorse Costco for having honored their in-house warranty in the past, free rotation and balance every 5K miles, etc. If you want Michelins, buy them on sale, of course.
Elaborate charts that show a prospective net difference in mileage of ~1 MPG seem to me a waste of time. If money is important (of course it is), calculate total cost of ownership, including projected mileage rating (e.g. 30K vs 60K). If you care about braking distance, wet and dry traction, then rolling resistance figures will become less important.
Finally, based on personal experience, just about any BEV is a better choice than just about any hybrid, but, of course, YMMV.
PS: I nearly bought a Clarity hybrid when they were first introduced... until I found I couldn't get comfortable in the front seat.