The Cadillac CT6 is one of the most anticipated debuts of the 2015 New York Auto Show, and Cadillac has just honed the edge of our interest: it will pack a 3.0-liter twin-turbocharged V-6 engine good for 400 horsepower and 400 pound-feet of torque.

That’s the top-line engine offering in the CT6, and it will also feature one other new aspect: cylinder deactivation. Turning off one cylinder per bank, the technology allows the engine to function as a V-4 under light loads. The CT6 engine will also feature stop-start technology. Cadillac claims this is the only twin-turbo V-6 engine in the world with both cylinder deactivation and stop-start.

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Sitting behind the new twin-turbo V-6 will be GM’s brilliant Hydra-Matic 9L90 eight-speed automatic transmission, versions of which are also found in the Chevy Corvette and GM’s pickup and SUV lines.

Peak torque in the new CT6 engine will arrive at just 2,500 rpm, holding there until 5,000 rpm, giving the car a strong mid-range torque plateau that should translate to easy pulling power in any gear, as well as an unflustered quality.

The new turbo V-6 also features some interesting turbocharger technology and design aspects, including low-inertia turbos with titanium-aluminide turbines, which translates to quicker turbo spool-up. A 9.8:1 compression ratio, forged crankshaft, reinforced pistons, hardened exhaust valve seat material, and sodium-filled exhaust valves also contribute to the engine’s performance potential—and may allow a fair amount of headroom for the aftermarket.

Cadillac is also announcing an all-new 3.6-liter V-6 to replace the current engine used in the ATS and CTS lines. The new 3.6-liter promises to be quieter and smoother, as well as offering cylinder deactivation and stop-start function. Output is stated at 335 horsepower and 284 pound-feet of torque, which Cadillac claims is the highest of any normally aspirated V-6 using regular fuel. Upgrades to the new engine over the previous version include: a stiffer aluminum block, a forged steel crankshaft, polymer-coated reduced-friction pistons, improved cooling, higher-flow cylinder head design, and a new variable displacement oil pump for improved efficiency.

The new 3.6-liter V-6 will be paired with an all-new Hydra-Matic 8L45 eight-speed automatic transmission.

Both the new normally aspirated V-6 and 8L45 transmission will make their debuts in the CT6 before filtering into the ATS and CTS ranges.

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