DETROIT – General Motors will unveil later today the ’14 Cadillac ELR, a 2-door luxury coupe and the second application of the auto maker’s fuel-saving Voltec propulsion system that combines battery power with a range-extending internal-combustion engine.

“ELR is an unprecedented combination of luxury, advanced engineering and progressive design in a coupe that is both sporty and environmentally friendly,” Cadillac Global Vice President Bob Ferguson says in a statement ahead of the unveiling at the North American International Auto Show here.

“This is a pivotal moment in Cadillac’s history, as we continue our product-driven expansion,” he says.

Cadillac’s U.S. sales fell 1.7% last year to 149,782 units from 152,389 in 2011, according to WardsAuto data, getting a late push by the fourth-quarter introduction of the ATS compact sports sedan and XTS large sedan. Until the arrival of those two vehicles, the brand had been operating shorthanded compared with its competitors through most of the year with a 3-product showroom.

The production-version ELR, introduced at the 2009 Detroit auto show as the Converj concept car, also confirms the plug-and-play promise of the Voltec propulsion system brought to market in late 2010 in the Chevrolet Volt EREV.

Chris Thomason, chief engineer on the ELR, says the Cadillac coupe copies the Voltec system from the Volt almost identically. It uses the same T-shaped, 5.5-ft. (71.7-m) long, 435-lb. (918-kg) 16.5-kWh lithium-ion battery and range-extending 84-hp 1.4L 4-cyl. gasoline engine.

The ELR’s duty cycle also matches the Volt, with an average all-electric range of about 35 miles (56 km) before the range-extending internal-combustion engine kicks on to generate electricity and power the car more than 300 miles (482 km) before it must be recharged or refueled.

The car includes a driver-selectable “Hold” mode to preserve battery power for urban conditions.

But because the ELR is a Cadillac loaded with creature comforts, a high-performance quotient and head-turning design elements, it will draw more battery power than its Chevrolet predecessor.

Achieving an acceptable range with the added weight of luxury amenities nearly killed the ELR two years ago, before real-world feedback from the Volt’s performance gave GM confidence to green-light the program.

“We exercise the battery a little more and do a little more with (electric) motor controls for more output,” Thomason tells journalists at an event inside the Warren, MI, GM Design center last week offering a sneak peek at the ELR.

The ELR will use about 70% of its battery before switching to range-extended mode, compared with the Volt that uses up much less before making the switch.

Maintaining a “buffer zone” within the battery charge is necessary to retain performance in extended-range mode, when the battery might be called on for extra power. With the Volt, GM chose to be conservative and keep the buffer zone relatively small, although for ’13 it was expanded slightly to give the car three more miles (5 km) of average range.

“More knowledge affords you the ability to use more (battery),” Thomason says.

The ELR battery takes about 12 hours to fully charge using its portable 120V charge cord and roughly 4.5 hours at a 240V charging station.

Output from the electric motors on the ELR rises to 154 kW (207 hp) from 111 kW (149 hp) on the Volt. Tweaks to the motor controls help the ELR deliver 295 lb.-ft. (400 Nm) of torque, or 12% more twist than the 3.6L V-6 gasoline engine in the Cadillac SRX cross/utility vehicle.

Top speed in the ELR is 100 mph (106 km/h), and it can travel from 0-60 (97 km) in about 8 seconds. In short, the ELR uses more battery power for enhanced driving dynamics at the sacrifice of potentially greater range.

Thomason doubts GM will carry the ELR buffer-zone and motor-output increases over to the Volt anytime soon. “There’s a niche element to the ELR,” he says. “Just because you can do something doesn’t always mean you should.”

The ELR receives a number of performance-enhancing technologies.

For example, the car leverages GM’s HiPer Strut front-suspension geometry, a lightweight and mostly aluminum setup resembling a McPherson design but with a shorter spindle length to reduce negative camber and put more tire rubber on the roadway.

HiPer Strut also greatly reduces the torque steer on cars employing front-wheel drive and featuring big, eye-catching performance wheels and tires such as the 20-in. cast-aluminum and Bridgestone-wrapped low-rolling resistance variety found on the ELR.

The ELR’s suspension takes advantage of a continuous damping control, which can adjust damping firmness in a split second to provide the best ride control over changing road surfaces.

Other key chassis items include:

  • A semi-independent rear compound-crank suspension with a Watts link incorporating weight-optimized trailing arms to absorb lateral forces and allow the suspension to handle vertical, forward and rearward motions.
  • Hydraulic ride bushings in the front and rear.
  • Anelectro-hydraulic regenerative brake system to recapture energy and direct it back into the battery.
  • Standard chassis-control systems such as antilock brakes, traction control and StabiliTrak electronic stability control.

The ELR uses a dual-pinion, rack-mounted electric power steering system with a ZF steering gear meant to provide optimal feedback and save fuel, compared with a traditional hydraulic power-steering system.

The car’s exterior design closely adheres to the Converj. “The Converj show car was our goal,” says Tim Kozub, lead exterior designer on the ELR.

That means the ELR boasts low, wide proportions with an aggressively raked windshield and back glass. Up front, the egg-crate-design grille gives the car an unmistakably Cadillac face. But because the car requires little air cooling, Kozub took the opportunity to nuance the closed grille with black pads.

Headlamps powered by light-emitting-diode technology provide the ELR with the “light blades” characteristic of modern Cadillacs. “We look at the (headlamp unit) as a gem case, with lots of detail displayed,” Kozub says.

A dramatic character line down the side of the ELR gives the exterior design momentum, and side mirrors include marker lights that do double duty as the charging indicator. Door handles are hidden in recesses. Fully LED rear lamps repeat the Cadillac light blades.

The ELR does not have a visible exhaust pipe. The Cadillac-brand, center high-mounted stop lamp sits prominently atop the rear deck, which also receives a functional spoiler.

Inside, the ELR’s 2+2 layout marries luxury and technology with a driver-oriented cabin, says Keith Fisher, the car’s lead interior designer. “Everything is in the perfect position for a fun-to-drive experience.”

The interior trim on display at the GM design center features a combination of standard decorative wood that is authentic and available carbon fiber with piano black accents.

Seating surfaces are covered what it calls a warm Cashmere-color of Opus semi-aniline leather, with 20-way power adjustment. Standards seats are 18-way adjustable, trimmed with lower grade leather.

A leather-wrapped and heated steering wheel included a leather horn cover, a first for Cadillac. In another first, the center-console-mounted dual cupholder features a power element opening and closing the cover with the push of a finger.

Other interior features include an 8-in. (20-cm) configurable instrument and driver-information display with four configurations, ranging from what GM calls “elegantly simple to technologically detailed”; fold-down rear seats creating room for longer items, such as skis and golf clubs; and choreographed LED-powered accent lighting.

Mark Adams, the former head of GM Europe Design and newly minted director of design for Cadillac and Buick, calls the ELR the “ultimate statement” of the brand’s Art & Science design philosophy.

“There is no other luxury car like this,” he says, characterizing the design as “youthful” and “expressive” with the added benefit of “guilt-free motoring.”

GM will build the ELR alongside the Chevy Volt and export market Opel Ampera at its Detroit-Hamtramck assembly plant, with the battery packs sourced from the auto maker’s nearby Brownstown Twp. facility.

jamend@wardsauto.com