Of the three vehicles using GM's newest hybrid system, we know rather less about the 2017 Cadillac CT6 Plug-In Hybrid than we do about either the Chevrolet Volt or the Chevy Malibu Hybrid.
But with first media drives of the conventional CT6 now published, we know a bit more than we did before.
For one thing, while the various gasoline versions of the CT6 large luxury sedan for the U.S. will be built at the Detroit-Hamtramck assembly plant, the plug-in hybrid CT6 will only be built in China.
DON'T MISS: 2016 Cadillac CT6 First Drive (Motor Authority)
That means that U.S. buyers of next year's CT6 Plug-In Hybrid will take delivery of cars made in China--the first time Cadillac has imported cars to sell in the U.S.
The plug-in CT6 will contain a battery pack assembled in GM's Brownstown battery plant, using LG Chem cells also fabricated in its plant in Holland, Michigan.
And the electric motors for its drive unit will be built at GM's plant in White Marsh, Maryland--which previously built Spark EV motors.
All of which points to an interesting global aspect to GM's plug-in hybrid luxury sedan: It uses technology designed, developed, tested, and built in the U.S., but the vehicle is destined primarily for the Chinese luxury market--and hence it's assembled there.
That's because local, state, and national government bodies in China now incentivize the sale and registration of so-called New Energy Vehicles, meaning battery-electric and plug-in hybrid cars and SUVs.
It's one tactic to address the highly hazardous air pollution in many parts of the country, and it's led to surging sales--though how many of the plug-in hybrids actually ever get plugged in remains an open question.
Last week, Shanghai-GM opened its first Cadillac factory in China, which will supply several vehicles that replace luxury models imported from the U.S.
The company is a joint venture between GM and its main Chinese partner, Shanghai Automotive Industries Corporation; the plant can built up to 160,000 vehicles a year.
China has been the world's largest car market for several years now, but its luxury sector is dominated by Audi, BMW, and Mercedes-Benz.
Both Cadillac and Ford's Lincoln are making strenuous efforts to establish themselves in China, where younger and first-time buyers may be less wedded to the German trio and more willing to try new luxury brands.
While the plug-in hybrid CT6 is aimed mainly at that market, it will be offered in small numbers in the U.S. to counter plug-in hybrid sedans from BMW and Mercedes-Benz.
The CT6 plug-in should arrive late this year or early next year, according to Cadillac executives interviewed by High Gear Media's Kirk Bell, who attended the CT6 drive event.
But it will be treated as just a separate powertrain option, not a different model (and it may not carry the cumbersome CT6 Plug-In Hybrid name).
Putting together numbers from a variety of Cadillac executives and sources, it appears that Cadillac anticipates fewer than 1,000 plug-in CT6 sedans a year will be sold.
That will represent 4 or 5 percent of the model's total sales, according to the company.
GM may issue more information on the technology specifics behind the plug-in hybrid Cadillac CT6 later this year, as it has done in the past with the Malibu Hybrid.
Both vehicles use variants of the latest Voltec drivetrain first launched in the 2016 Chevrolet Volt.
The hybrid Malibu has a much smaller battery pack and no plug, while the Cadillac has a differently shaped battery pack with the same capacity as the Volt's, 18.4 kilowatt-hours.
Its range has been quoted as "about 30 miles," but it's unclear whether that applies to U.S. or Chinese test routines.