Cadillac CT6 Plug-In Makes Going Green Easy, Mostly

Future large luxury will come with a plug, because electrification is the sole option for the industry’s tony brands to maintain their conspicuous opulence amid an impending global emissions crackdown. Goodbye growling V-8s, hello whirring electric motors.

And you know what? If the ’17 Cadillac CT6 Plug-In serves as any evidence, perhaps life off the gas nozzle and on the electric grid won’t be that boring after all.

The CT6 plug-in, which joins similar electrified large-luxury sedan offerings from brands such as Mercedes-Benz, BMW and Porsche, is delightful to drive, delivers outstanding fuel economy, and, while it may omit some luxury-car staples in the name of efficiency, it is as comfortable and connected as anything on the road.

The CT6 uses lithium-ion battery technology deployed elsewhere within the General Motors portfolio for several years, most notably on the more budget-minded Chevrolet Volt extended-range electric vehicle. The 18.4-kWh pack in the CT6 provides owners with 31 miles (50 km) of fully electric range, give or take a couple miles for weather, driving habits and conditions. A 2.0L turbocharged gasoline direct-injection 4-cyl. boosts its range to an EPA-estimated 440 miles (708 km).

A dual-motor electric variable transmission provides drive to the rear wheels and combines with the engine for a total system output of 335 hp and 432 lb.-ft. (586 Nm) of torque.

WardsAuto editors logged 433 miles (697 km) of everyday driving over eight days last month, and the CT6 returned 49.6 mpg (4.7 L/100 km) and 59.3 mpg-e (4.0L/100 km), which is a couple ticks shy of its EPA-estimated 62 mpg-e (3.8L/100 km). The plug-in’s fuel economy compares to a peak 30 mpg (7.8 L/100 km) highway in a CT6 outfitted with a standard 2.0L turbo, so there’s a big step up in efficiency with the electrification.

Taken another way, the average driver of the CT6 plug-in would spend $1.76 to travel 25 miles (40 km). That’s nearly $0.75 cheaper than the average gallon (3.8 L) of gasoline in the U.S. There’s no anxiety over running out of battery charge and getting stranded with nowhere to plug in, either, because the gasoline engine can do all the work if necessary.

The CT6 plug-in is a boatload of fun to drive, too. The car’s propulsion controls do a masterful job of maximizing electric range, even at highway speeds. The hefty sedan is quick off the line with the electric motors pouring out torque rivaling the creamiest of big-displacement gasoline engines. GM estimates the car will sprint 0-60 mph (97 km/h) in 5.2 seconds, which according to third-party testing is 0.7 seconds quicker than a CT6 outfitted with a twin-turbo V-6.

There was an occasional hiccup in the system. When cruising at highway speeds and thumping on the throttle to pass or enter a freeway, the car’s controls were sometimes indecisive.

But during those miles of pure electric power, the car moves along as quietly as a big, prowling cat. Dip into the throttle, and it springs to action just as ferociously.

Myriad high-resolution gauges chart the car’s efficiency and the propulsion symphony occurring under its skin. The switch from electricity to gasoline is nearly imperceptible, although there is a mechanical drone every now and then under battery power, presumably from the power inverter.

Colorful gauges within the instrument panel offer drivers a quick reference point for the battery’s state of charge, estimated electric range and combined range with the gasoline engine. A deeper dive into the propulsion system resides within the CUE infotainment system atop the center stack. It details state of charge, power flow and charging status and estimates of how long a full recharge may take. A detailed energy-consumption history also is available through CUE.

Charging Woes, Trunk Trouble

GM estimates the CT6 plug-in’s battery pack will recharge from full depletion using a 240V station within 5 hours. That was spot-on with the Level II-unit in the WardsAuto garage. But recharging from a standard 120V household outlet will take up to 20 hours.

Our experience was mixed with 120V. One editor could not charge at home because the CT6 plug-in’s charge cord indicated an improper ground. That was a first for a fleet of EVs to pass through his garage, but the improper ground also is a default message for a number of issues. A second editor had no problem charging at home.

GM engineers did a fine job with the regenerative-braking system. There is a lot of bite to the brakes and only a small degree of the resistance found in other hybrids, perhaps because the CT6 plug-in uses a combination of traditional hydraulic braking with deceleration from the transmission’s electric motors. The result is good brake feel with energy recaptured to improve fuel efficiency.

Drivers can choose between three operating modes: Normal, Sport and Hold. Normal is for everyday driving and maximizes comfort, while Sport dials up steering feel and pedal mapping for more spirited motoring. Hold allows the driver to reserve electric power for city conditions when the car operates most efficiently.

Small trunk among sacrifices with CT6 plug-in.

Drivers can choose how aggressively to use regenerative braking. Four progressively stronger modes can be accessed through steering-wheel paddles, ranging from the feel of downshifting a manual transmission when exiting a freeway, for example, to one-pedal driving where maximum energy recapture occurs.

Driving with a single pedal probably is not for everyone, especially longtime luxury-sedan owners, but it genuinely reduces the fatigue from going back and forth between the brake and accelerator in traffic jams. It also takes fuel efficiency to another level.

The CT6 plug-in is available in the U.S. with a single trim level, which includes items such as rear-seat infotainment with power-operated DVD screens, a driver-assistance package with excellent night-vision technology and a host of active safety items. A panoramic sunroof also is included and a Bose 10-speaker sound system holds its own.

But energy preservation is paramount with the CT6 plug-in, so there are some unavailable items most luxury buyers generally would expect as the price of admission to the segment. For example, controls exist for massaging seats but are not installed and neither the premium 34-speaker Bose Panaray audio system, adjustable rear seats nor the quad-zone climate control system are available.

Lots of luxury inside CT6 plug-in.

The CT6 plug-in also has a trunk no self-respecting mobster would ever put into service. Since the battery pack is installed behind the rear seats, the trunk hardly accommodates one golf bag. So whether you’re looking to do a job for the family or host your foursome, the CT6 plug-in would not be the most convenient option. Big car, small truck.

Otherwise, CT6 plug-in owners will hardly miss the largesse of their far-less-efficient cousins who burn oil alone. There is a robust OnStar 4G LTE Wi-Fi connection, as well as Apple CarPlay and Android Auto capability. Linking to the Wi-Fi and Bluetooth is a snap.

And while the massaging seats are not there, the 16-way power-adjustable front driver and passenger seats are built for the long haul. The interior is a veritable tomb of solitude away from the outside world, while its superb, full-speed adaptive cruise control practically tempts drivers to doze off. The exterior flashes with unmistakable Cadillac style.

GM expects to sell just a handful of the cars in the U.S. Its primary market is China, where it is built and the regulatory regime demands plug-in technology from luxury brands if they want to play there. But if you’re a well-heeled Yank looking to go green, the $75,000 CT6 plug-in is among the most efficient in its class. It’s the best value, too, both before and after an available $7,500 tax credit. – with Bob Gritzinger

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'17 Cadillac CT6 Plug-In Specifications