At the 2009 NAIAS, GM unveils the first potential variant of its 2011 Volt extended-range electric car—and it's a Cadillac.
Winner of multiple NAIAS design awards, including Best Concept by the elite Eyes on Design judges, Cadillac’s Converj was certainly a showstopper. Development of the tautly rendered four-passenger coupe—“the modern vision of a personal luxury 2+2,” said Bob Lutz, General Motors Vice Chairman of Global Product Development—was led by Simon Cox, Director of GM Advanced Design. Cox also was responsible for the equally dramatic 2000 Imaj concept.
Many showgoers viewed Converj’s aggressive overall form, with its bold detailing (including vestigial tail fins), as a logical extension of the Cadillac CTS Coupe unveiled at NAIAS ’08. According to Cox, the new concept coupe’s forward-leaning profile pushes the brand’s signature Art & Science design language to a higher plane. But Converj’s greater significance lies under its sharply creased skin—an extended-range-hybrid electric powertrain based on the 2011 Chevrolet Volt.
“It [Converj] clearly shows what a Cadillac electric vehicle could look like,” said Lutz, “and indicates that global luxury customers can have a car that has both strong design and electric propulsion with a total range of hundreds of anxiety-free miles.” Indeed since Volt’s 2007 debut, AEI’s Editorial Director has argued for applying the E-REV powertrain to a Cadillac model.
E-REV now has its own brand name: Voltec. For Converj, it consists of Volt’s flex-fuel-capable four-cylinder combustion engine/generator, a 16-kW·h battery pack containing more than 220 lithium-ion cells, and an electric drive unit. The configuration is technically a series-type hybrid. Its front drive wheels are always propelled electrically, whether operating on battery power or in extended-range mode using the engine-generator to create onboard electricity. (The driveline also can be configured for all-wheel drive, the likely application for a Cadillac version, according to GM engineers.)
As installed in the Converj, the Voltec system delivers 273 lb·ft (370 N·m) of peak torque and 120 kW of power—sufficient to propel the car to a maximum speed of 100 mph (161 km/h). The 375-lb (170-kg) T-shaped battery pack measures nearly 72 in (1828 mm) long. It is capable of providing up to 40 mi (64 km) of pure-electric, zero-emissions driving range before the pack’s charge has been depleted (at which time the engine-generator engages), or until the car is plugged in to the electric grid to charge the battery. Recharging time as proven on Volt mules is less than 3 h at 240 V, or about 8 h from a 120-V home outlet.
Converj’s pack is located longitudinally along the center tunnel and under the rear seats. This integration, similar to Volt’s, treats the battery as part of the vehicle structure. GM’s simulation data indicate that the central placement provides the pack greater protection.
Converj measures 182 in (4623 mm) long and 74 in (1880 mm) wide. Wheelbase is 108 in (2742 mm), and the car rides on 21-in front and 22-in rear wheels. The suspension features McPherson struts and a rear twist beam axle, augmented by GM’s Magnetic Ride Control. Steering is by an electric power-assist system.
Solar panels integrated into Converj’s all-glass roof help offset the car’s electric-accessory draw. Overall aerodynamic drag is reduced using a full belly pan, low-profile rearview cameras replacing conventional exterior mirrors, and road wheel geometries that help reduce bodyside turbulence. The car’s grille openings were also designed to reduce drag.
Converj’s interior materials are made predominantly from renewables, including wool-blend carpeting, a silk headliner, and synthetic suede made from post-industrial content. The instrument cluster is reconfigurable and driver displays feature LEDs with touchscreen operation.
While GM has not decided whether to produce Converj, company executives said greater scale is being planned for the Volt program as part of the automaker’s revitalization plan. One key to that strategy is the decision, also announced at NAIAS, to manufacture the integrated battery packs at a new facility in Michigan beginning early next year. The battery-pack plant is expected to be located near Volt’s Detroit-Hamtramck assembly plant. GM also announced it will source the lithium-ion cells from LG Chem’s Compact Power Inc. group.