And as others have mentioned, it's taken advantage of newer technology that allows six of pistons to be turned off.

The engine basically sounds like two in-line six cylinder engines that share many common single engine features but with the ability to shut off one side and use power from the remaining side.

So hypothetically, you fly up to altitude and climb using all 12 cylinders, then cruise on six.

That could be where the fuel efficiency is being notched up versus burning all 12 cylinders at all times.

Kinda like how people are still amazed variable displacement engines took them from 10mpg to 18-20mpg. It's also likely the engine has a number of other more recent innovations included too. Variable valve timing, etc, etc. A lot of new rather exciting new engine technology has come out in the last 20 years.

It's much like when we went from naturally aspirated aka carbs to electronic fuel injection/ignition.

Naturally aspirated != carb.

You can have a naturally aspirated engine with electronic (even direct) injection, or a turbocharged engine with a carburetor, or any other combination.

True. Naturally aspirated simply refers to the lack of a turbocharger/supercharger pressurizing atmospheric air as "boost".

I just wish carbureted was an easier word to spell after not using it for months at time.

which pretty much keeps it restricted to overland only. it took a long time for the FAA to permit twins to fly across the ocean? ETOPS (Extended-Range Twin Engine Operational Performance Standards) is just what it says, twin engine but is there any possible means a passenger carrying single engine could get certification? Now as an unmanned cargo drone it might get this permission.

You can fly a single over the ocean, you just have to carry extra equipment.