The heart of Cadillac's new CT6 2.0E Plug-In Hybrid (yes, that's the badging on the car), is a new longitudinal transmission that has evolved from the good old two-mode hybrid transmission (developed with Chrysler and BMW) that made its debut at the 2007 L.A. auto show. Then as now it employs two electric motors (each of which now produces 100 hp, up from 80), connected to the road via a four-speed automatic transmission. We're told the current setup quite closely resembles that of the Lexus LC 500h, which connects the two motors via a planetary gearset and allows for pure EV operation, hybrid gas/electric operation with the engine simply providing energy to one of the motor/generators, or hybrid running with the engine helping the e-motors turn the wheels. The various gear sets are continuously blending inputs so it never feels like a four- or eight-speed transmission.

As the nomenclature suggests, the engine is GM's increasingly ubiquitous 2.0-liter turbo four, which gets few alterations save for a higher idle speed (1,400 rpm versus 950) that allows it to generate power for the battery pack at idle. Altogether, given the different power peaks of the electric and gas machines, combined output is pegged at 335 hp and 432 lb-ft of torque.

2017 Cadillac CT6 20E Plug In Hybrid front end

Electricity comes and goes from an 18.4-kW-hr lithium-ion battery pack (using the same chemistry theMotor TrendCar of the Year Chevrolet Bolt EV uses) situated behind the rear seatbacks. The pack gets loaded in from below, and its lower tray is a structural element. The pack weighs 400 pounds and shifts the weight distribution to 44/56 percent front/rear. It's also bulky enough to consume precisely 5.0 cubic feet of luggage space. It also consumes space where the Bose Panaray rear shelf speakers and the Active Chassis System's active-rear-steering would otherwise live, so those options are not available, nor will the forthcoming Super Cruise semi-autonomous driving system be available (rear steering is a redundant feature of that system). Oh, and you also can't have big wheels and tires—20s can't shoulder the load, and while 19s can, they ride too poorly when aired up sufficiently for the added weight. So 18s it is.

2017 Cadillac CT6 20E Plug In Hybrid steering wheel

The battery can support up to 30 miles of reasonably gentle EV driving (60 percent or more throttle fires the engine) at speeds of up to 78 mph (just over half-way to the car's 150-mph top speed). The fuel tank shrinks by 4.3 gallons to 15.2, which Cadillac claims will provide a 400-mile overall range and an associated 65 mpg-e rating. Fully electric heating and cooling of the cabin are available to ensure comfort in EV-mode. Speaking of modes, there are three: normal (balanced performance and comfort with maximum EV range and fuel economy), sport (engine remains on, torque response is more aggressive, and steering is stiffened up a bit), and hold. The last mode preserves EV range for use upon arrival in an EV-only city center for example (these are springing up in China, where the CT6 2.0E will also be sold). Paddle "shifters" allow the driver to toggle the amount of regeneration up and down, with max regen providing up to 0.18 g of deceleration.

Look for the 2.0E Plug-In Hybrid variant to hit showrooms in early 2017 priced at $76,090.

2017 Cadillac CT6 2.0E Plug-In Hybrid
BASE PRICE	$76,090
VEHICLE LAYOUT	Front-engine, RWD, 5-pass, 4-door sedan
ENGINE	2.0L/265-hp/295-lb-ft turbocharged DOHC 16-valve I-4 plus two 100-hp electric motors; 335 hp/432 lb-ft comb
TRANSMISSION	Electric cont. variable auto
CURB WEIGHT	4,050 lb (est)
WHEELBASE	122.4 in
LENGTH X WIDTH X HEIGHT	204.1 x 74.0 x 57.9 in
0-60 MPH	5.2 sec (mfr est)
EPA CITY/HWY/COMB FUEL ECON	Not yet tested
ON SALE IN U.S.	Early 2017

2017 Cadillac CT6 Plug In Hybrid front three quarter