Keeping Pace with the Volt

July 15, 2008

General Motors is furiously working to meet its 2010 production deadline for the Chevrolet Volt, the former concept car and soon to be corporate identity. The car, alternatively called an electric, plug-in hybrid, or extended range vehicle, is racing to the design finish line, and I recently met with Volt engineers in Warren, Michigan to get the latest on its evolution.

Bob Boniface, Director of Design at the E-flex (GM's name for its fuel and electric power train system) Studio said that the design of the Volt is basically nailed down. Any further changes will be for manufacturing viability, he said. (The same studio also has designed a recent model of the Camaro.)

The Volt has gone through many iterations since it was unveiled in January 2007. Originally the Volt looked like a sports car, but now it looks more like a typical sedan, comparable in interior and exterior size with the Toyota Prius or Honda Civic. To my eye, it is a conventional sedan and less striking than the Prius, but what's inside is what really matters.

Unlike other sedans, the back seat only has room for two adults because of the battery pack that runs through the middle of the vehicle. "It is a tight fit" in the back, Boniface said, conceding that the car won't be for everyone.

Boniface said GM Vice Chairman Bob Lutz told him that he was tired of the company not being viewed as a technology leader. "When you think about Toyota, you see a Prius, when you think about GM, you see a Hummer." The media has only reinforced the opinion that some consumers have, according to Boniface.

Lutz wanted to put a new face on the company and requested a technology-driven car. Several outlandish models were presented to him, but he responded "No, you don't understand, I want an electric car." Three models were considered, and Lutz chose Boniface's group's design.

The Volt uses an electric generator to charge batteries, which provide the vehicle's power at all times. The Volt is more energy efficient than today's vehicles because unlike combustion engines, which rev up and down, when the generator is needed it provides power in a constant, optimized way (except for when charging the batteries on a steep incline), Boniface said.

While in my previous discussions with GM the company resisted classifying the Volt as a plug-in, during this meeting Boniface said the Volt is "more of a plug-in than a plug-in hybrid" because electric power will provide locomotion for much more of the time that the vehicle is operated. The Volt has an eight-gallon tank, but consumers with short commutes will likely "drive it off the lot with a full tank and won't put any gas in it," he said.

Boniface said the amount of power consumed when driving 40 miles per day in the Volt will be about as much as it takes to power a water heater -- a welcome contrast to the cost of driving on gasoline today.

Most of the design work for the Volt is done on one-third scale models. Boniface said stickers that resemble paint are applied to the clay models, which are taken outside for inspection and comparison with other cars. "The car always looks different first time you put it on the road," he told me.

The design team has worked closely with the aerodynamics group to meet the goal of the vehicle going 40 miles on all-electric power. Design changes are modeled by computer to understand their effect on aerodynamics. The suggested changes are made to the full-size model by a machine that can change the shape in as small as 100-millimeter increments.

Every edge and line can greatly affect the aerodynamics, so design was a continual back-and-forth process to reduce the Volt's drag. Nina Tortosa, a GM Aerodynamicist who had previously worked on the Corvette and fuel cell vehicles, said optimizing the Volt's shape has been by far the most challenging assignment of her career. Refining the Volt required dozens of 12-hour days and long stints in the wind tunnel to make sure that reality matched the design algorithms. If it didn't, it was back to the drawing board for new ideas. Tortosa said she has spent more than 600 hours in the wind tunnel, but she enjoys "crawling around on the floor."

Small changes can add up in energy savings. Boniface said the airflow through the grille and the vehicle were continually tweaked to maximize airflow. "It's much more complex than a traditional car," he said, citing the five separate elements that need to be cooled, including the battery pack, liquid cooling for the engine, the electric drive unit, the AC evaporator, and the power electronics.

For every 10 counts of drag, the vehicle can go an extra half mile on battery power alone. For example, slight changes to the side mirrors and the lip of the car result in saving nine counts of drag, which would have otherwise required losing 22 pounds from the vehicle.

The model I was shown (GM did not allow photographs to be taken) features a dashboard with two video screens -- one for entertainment and one for information about the vehicle's energy consumption. The energy screen -- which can be customized -- will use animations to display energy use, miles per gallon, gasoline displaced and remaining charge time among other data. The Volt will have a GPS unit and will more than likely have GM's interactive OnStar communications system as well. The onboard charger can be programmed to recharge the batteries based on vehicle owner's utility rates, a feature that will sit well with the cost-conscious.

Gadget geeks and "hypermilers" will also like being able to view all of the vehicle information online so that they can track their fuel savings and brag about it to friends or on their blogs. The Volt will also have a USB ports, Bluetooth wireless networking, and an iPod jack.

GM is running a two-year test on the Volt's lithium ion batteries to make sure they can tolerate daily recharging. The batteries are charged from 30 to 80 percent full during the cycle test which will simulate 150,000 miles of driving, according to Lance Turner, a GM Battery Test Engineer. The batteries can be recharged in as little as three hours through a 220 volt plug. GM has been designing the Volt without knowing the exact battery that will be used in the production version, a huge leap of faith for the company.

I'm convinced that when -- not if -- GM or one of the plug-in hybrid makers delivers on the promise of a vehicle that can satiate daily driving needs on battery power alone, they will be starting a revolution that will reshape transportation as we know it. GM desperately wants to be first to market (with Toyota in hot pursuit), and so far they seem on track.

(Photos courtesy GM.)