WARREN, MI –Co. engineers continue to tweak the driving dynamics of the new-for-’11 Chevrolet Volt extended-range electric vehicle as production of salable units draws nearer, saying the meticulous process may even stretch beyond shipments to dealers.
“We will continue tweaking after the vehicle is launched,” Doug Parks, vehicle line executive-Chevy Volt, tells Ward’s at a stopover Monday during media test drives of the car. “We want to learn from (owners).”
GM will ship the first units to dealers late next month, suggesting production of those cars likely will begin in a matter of weeks.
The decision to perform calibrations to software controlling items such as steering, throttle and braking so late in the game underscores the complexity of the Volt’s propulsion system.
It also demonstrates the difficulty of delivering a radically different product to consumers in a package they’ll find entirely familiar.
The Volt is capable of traveling between 25 and 50 miles (40-80 km) under battery power. After eclipsing that range, a 1.4L internal-combustion engine runs a generator to provide additional electric power and take the car a total of 350 miles (563 km) before the car’s driver must either plug-in for more juice or fill up with gasoline.
But electric motors driving the Volt’s wheels, for example, provide torque delivery unlike a traditional ICE powertrain. The Volt’s 273 lb.-ft. (368 Nm) of torque arrives almost instantly, and engineers must make sure it comes on in a linear fashion. They work in a window of time measured in milliseconds.
Months of software calibration smoothed out introduction of the ICE when entering range-extended mode. Early in the Volt’s development, the transition arrived like a thunderstorm in August. But today, most drives will realize the change only if they are watching gauges on the instrument panel.
Parks says even with as many miles as GM engineers have put on the Volt driving it under all weather conditions, altitudes and terrain, calibration probably won’t be perfect until the auto maker gets feedback from everyday consumers.
Earlier this month GM enlisted 15 people, comprising EV experts and enthusiasts and celebrities, to serve as a customer advisory board to help with validation. The group will test the Volt as part of their daily routines over a 3-month period. In addition to driving dynamics, the group will report back their experiences charging the car.
Vehicles sold without the newest calibrations could receive a “software flash” during a regular service.
Parks says suppliers also continue to ramp up production. That means more “real parts” will arrive at the Volt’s Detroit-Hamtramck, MI, assembly plant, instead of the “hand-made” ones the plant has been receiving. As such, the likelihood of imperfection rises, so the manufacturing team is continuing to learn how to spot a potential problem part.
The team also is continuing to “tune” the Volt’s body panels, as it strives for optimal fit and finish.
Park also reports GM still is working with the Environmental Protection Agency on a label for the Volt. He expects a single number between 25 and 50 miles on the sticker to indicate the Volt’s range under battery power and a number stating combined-cycle miles-per-gallon in the “middle to upper 30s.”
The sticker also could contain a miles-per-gallon equivalent number, and discussions continue over including carbon-dioxide emissions.
Parks expects a final sticker within two to three weeks and says it will reflect the new design of the labels coming for all cars next year.
Crashworthiness is another important element of the vehicle label. Park says even if the Volt does not rate an overall 5-star rating from the National Highway Traffic Safety Admin., he considers it a lock for a 4-star designation.
NHTSA revamped its crash-testing procedures for the ’11 model year and only two of 35 models tested so far have earned a 5-star rating.
Still, Parks admits, five stars on the sticker could help allay any trepidation consumers might have about buying an EV.
Interestingly, one safety modification to the Volt includes a narrow break in the middle of its massive battery pack to help disperse crash energy in a side-impact collision. The battery pack also has a switch accessible to emergency responders to cut power after a crash.
But where the Chevy Cruze platform mate receives 10 airbags, the Volt features eight. Since the EV carries four passengers instead of the Cruze’s five, Park says rear passenger seating moves farther inboard and makes rear-door airbags unnecessary.