Cadillac CT6 Plug-In Hybrid: Big Battery, More Electric Range

As predicted, the plug-in hybrid version of the 2016 Cadillac CT6 large luxury sedan was released today at the Shanghai Motor Show, using an adaptation of GM's second-generation Voltec hybrid system.

What wasn't predicted was the startling size of its battery pack: 18.4 kilowatt-hours, identical to that used in the 2016 Chevrolet Volt.

That means Cadillac is fitting a battery that's essentially double the size of any other plug-in hybrid on the market today--and should probably achieve 30 or more miles of electric range with it.

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Unlike the Volt, however, the CT6 plug-in hybrid will switch on its engine under higher loads, according to the GM press release.

That engine is a turbocharged 2.0-liter four-cylinder with direct injection, presumably a variation on the same engine in the non-hybrid four-cylinder CT6 announced at the New York Auto Show three weeks ago.

While GM didn't break out the power of the engine or the two electric motors in the Voltec hybrid drive system, it said the combined system produces 335 horsepower (250 kilowatts) and 432 lb-ft of torque.

The battery pack is not the "T-pack" used in the Chevy Volt, which sits in the tunnel between the front seats and under the rear seats. Instead, according to Cadillac, it's located "between the rear seat and the trunk," effectively between the rear wheels.

Like the Volt pack, the CT6 plug-in hybrid battery will use GM's "proven active thermal control system that maintains electric range over the battery system’s life," it said.

While the U.S. release notes that range estimates will be provided near to the U.S. launch of the car, the Chinese release cites a range of "greater than 60 km" (more than 37 miles).

That number, however, is likely to fall on the more challenging U.S. EPA test, which is adjusted to reflect the agency's best estimate of average real-world use.

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"Cadillac expects the fuel economy of the CT6 PHEV to be more than double that of the car’s conventional engine offerings" in the U.S., Cadillac said, "as measured by miles per gallon [MPGe] equivalent."

The Chinese model will be rated at approximately 2.0 liters per 100 km, it said, which translates to 118 miles per gallon.

To its credit, however, Cadillac underscored the different testing cycles: "Standards for measuring vehicle fuel economy differ between China and other global regions."