Latest video from Brian, the Karma owner who did that review. Some of the math is not quite right, but judge for yourself
526.7 / 0.9 = 585.22, not 579 something.
I also wonder if his handwave of carbon footprint for extracting oil from 2 miles under the ocean, shipping it, processing it is really the same as extracting natural gas's extraction, shipping, and processing, or coal for that matter.
I'm also concerned that we talk about CO2 footprint without talking about actual pollutants. Isn't coal pollution nastier than natural gas?
His ability to charge at home during the afternoon is relatively unique - most people drive to work. Maybe that's why the Karma's limited EV range doesn't phase him? With a 42 mile round trip commute, I'd be at the cusp of using gas every day, definitely if I ran errands on the way home, and definitely as the range decreases from 40 miles to 36 miles. Of course, as I tend to be a hot-foot, some (minor?) additional gas usage there as well.
One question I have is that if, say 20% of a Karma's mileage was gas only (trips to Tahoe, etc.), then wouldn't that mean the battery life would be more like 120K miles than 100K miles? That is, you really only want to count the miles driven on the battery, not on the ICE in figuring out degradation.