The Cadillac CT6 PHEV will be the first in an assortment of plug-in models to follow.

Cadillac has pulled the wraps off a second version of its new CT6 sedan, unveiling a plug-in hybrid version of the flagship model at the Shanghai Motor Show.

The announcement confirms a report by TheDetroitBureau.com earlier this month that also revealed the CT6 PHEV will be the first in a broad range of plug-in hybrids planned by Cadillac covering most of its product line-up by the end of the decade.

Unlike the current Caddy ELR, however, the Cadillac CT6 PHEV will deliver performance equal to that of the twin-turbo V-6 that will be the top-line gasoline engine for the full-size luxury sedan. But it is also expected to double the fuel economy, which could translate into a combined city/highway rating in excess of 40 miles per gallon.

“The advanced Plug-In Hybrid system is a key addition, providing a combination of exceptional fuel economy, crisp acceleration and strong electric-driving range,” said Cadillac President Johan de Nysschen. During the unveiling at the Shanghai show, the executive said the CT6 provides, “an ideal platform for Cadillac to offer its first plug-in hybrid.”

More precisely, it will be the second plug-in, though de Nysschen might be forgiven for trying to forget the ELR which generated barely 1,100 sales last year. The South African-born executive recently told TheDetroitBureau.com that the ELR will play out its lifecycle – which should last another four years or so – but will not see a direct replacement.

(For more on the NY debut of the new Cadillac CT6, Click Here.)

That reflects a broad shift in the luxury market away from plug-based vehicles that are fuel-efficient but slow. Going forward, most makers – notably including BMW and Mercedes-Benz — intend to put as much of a premium on performance as mileage as they unleash a flood of new PHEVs.

While officials don’t plan to release specific fuel economy numbers until closer to the launch of the Cadillac CT6 PHEV, it is expected to yield somewhere in excess of 40 mpg, which would not lag far behind the much smaller, less lavish and decidedly slower Toyota Prius.

The Caddy plug-in will be powered by a combination of two electric motors and a turbocharged 2.0-liter four-cylinder gas engine. The package will make 335 horsepower and 432 pound-feet of torque. By comparison, the twin-turbo V-6 gas model is rated at 400-hp and 400 lb-ft.

The hybrid package will deliver power through a new electric variable transmission through the rear wheels. Cadillac has not offered details on the new EVT, but claims the gearbox, along with the use of twin electric motors, helps ensure a smooth driving experience.

Range in electric mode also hasn’t been released. But Caddy says the 18.4 kilowatt-hour lithium-ion battery pack will be tucked in between the rear seat and the trunk.

While the battery pack is likely to add 100s of pounds to the base weight of the CT6, Cadillac has a potential advantage in the fact that it has put a premium on “lightweighting” the sedan. During the debut of the CT6 at the New York Auto Show earlier this month, de Nysschen noted that while the sedan is the size of a BMW 7-Series it weighs only about as much as a comparable 5-Series model.

(Automakers put their products on a diet in bid to boost fuel economy. Click Here for more on this lightweighting trend.)

Caddy confirmed it will offer the new CT6 PHEV in the U.S. as well as in China where the government is aggressively promoting electric propulsion in an effort to reduce endemic smog problems in cities like Shanghai and Beijing.

Facing tough new emissions and mileage standards around the world, a growing number of luxury automakers are planning to launch plug-based products in the years ahead, including manufacturers as diverse as Aston Martin and Bentley, the latter set to introduce a PHEV package for its upcoming Bentayga SUV. Mercedes, meanwhile, recently announced it will add 10 plug-in hybrids by 2017, starting with the new 2016 GLE sport-ute.

As for Cadillac, de Nysschen told TheDetroitBureau.com the plan is to add a PHEV for virtually all of the many new models the U.S. luxury maker will launch by 2020.

Several company sources say they expect only modestly better sales for the CT6 PHEV than they’ve seen with the Cadillac ELR, but that could increase as overall awareness of the technology increases in the years ahead. Pricing — not yet announced — will likely also have a significant impact on demand, analysts have said.

(Cadillac boosts performance, cuts price, hoping to increase sales of ELR plug-in. Click Here for the full-story.)