High Voltage or brownout? Ars checks out the Chevy Volt

Beyond hybrids

The invitation contained one obvious hint that the target audience was a bit different than the typical invitees to a New York City tech event: it offered free parking to drivers. Last night, General Motors held a press event with an audience that included reporters that serve a range of audiences, including car junkies, the green community, and general technology enthusiasts. The focus: a car that should appeal to all of them, one that the company has bet its future on. After killing off the electric car in its EV1 incarnation, GM hopes to resurrect it in the form of the Chevy Volt.

After having shown a concept model at auto shows that was basically a construct put together out of parts of existing vehicles, GM claims that what we saw last night was supposed to be the final design that would actually make it to market. The car was nonfunctional—as one of the engineers said, they have more important things to do with the batteries than ship them to New York—but intended to give a real impression of what a buyer might actually drive off the lot sometime in the next few years. GM has tackled the Volt project with a mix of marketing, engineering, and technology development. Last night's event provided a little of all of them, but we'll focus primarily on the latter two.

The Volt vs. the hybrids

GM is adamant that people recognize the Volt for what they consider it to be: despite the presence of a flex-fuel engine, this is an electric vehicle, not a plug-in hybrid. This has a lot of interesting consequences, but one of them is simply that it radically changes the driving experience. Unlike internal combustion engines, electric motors have full torque even at their lowest speeds. Hybrids have this to a certain degree, but they have a relatively low-output motor and make up for the difference by kicking in their gasoline engine as needed. That feature of hybrids, which the GM staff were happy to call "jarring," won't happen with the Volt. Its engine simply doesn't ever directly interact with the driveshaft, but is instead used to power a generator.

Another consequence is that, even with a plug-in hybrid, it's essentially impossible to do any significant driving without having the gasoline engine kick in. For the Volt, the gasoline engine will only kick in if the battery's charge drops to its minimum acceptable level (more on that later). For most people, that means the car will rarely burn gasoline; for many commuters, GM estimates that the engine will never switch on. One odd consequence of this is that nobody's quite sure how to regulate the Volt. It will often be zero emissions, but not always, and traditional MPG ratings are likely to be completely dependent on usage patterns. GM is currently negotiating with the EPA, but is hoping to see the vehicle placed in an entirely new regulatory category.

One nice feature about the engine being disconnected from driving the car is that, when it runs, it can always run within its most fuel-efficient power envelope. There's some efficiency lost in the conversion to electric power and battery charging, but the Volt will get over 30 miles to the gallon when it is running (indirectly) on gasoline. Frank Weber, the Volt's chief engineer, was oddly cagey about how big the gas tank would be, but Bob Boniface, who is the car's design lead, suggested it had a capacity of eight or nine gallons. Regardless, they expect that it can keep the car going for an extra 300+ miles after the charge runs down.

Throwing Volts around

The Volt does have one thing in common with hybrids: it uses regenerative braking to grab back some of the power that would otherwise be lost when the car is brought to a halt. According to Weber, this actually allowed the design team to avoid the expense and engineering challenge of going with exotic, lightweight materials to keep the range of the car above its 40 miles-per-charge target. Lighten the car up too much, and the braking doesn't yield as much juice, so limited returns kicked in quickly.

But the centerpiece of the Volt is its T-shaped, 16Kwhr battery. The battery will use prismatic lithium cells—these are already available commercially, so this part of the technology is relatively conservative. GM is working with two companies that are taking different anode/cathode approaches: A123 Systems' nanophosphate cells and an alternate approach from Compact Power. According to Weber, the technology is less important than build quality. The Volt can get by with something reasonably close to current technology, but it can't afford to have many of the millions of individual cells in the battery fail.

Long term, GM is hoping to see sales of the Volt be sufficient to kick off a competition among battery makers to supply better and cheaper technology. During the development stage, however, the company is doing joint work with these two suppliers. On the plus side, that will leave GM with a degree of control over the results and how they are licensed to any automotive competitors.

To extend the battery's usable lifetime, the management software will avoid having it discharge below 50 percent of its capacity. GM estimates that this will give it a 10-year lifespan at 15,000 miles of driving a year. The battery can be replaced—there's a kill switch inside the car, and bolts underneath allow it to be detached from the frame and lowered out of the car. But the car is basically built around the structure of the battery, and removing it isn't simple. When I asked Weber about whether future battery tech might enable a situation where depleted batteries could be quickly swapped out for a fully charged one, he wasn't especially excited about the idea. Faster charging, he felt, would be a better goal. If the weight and size came down, it would be better to use that for greater design flexibility, he felt.

The biggest challenge, according to both Boniface and Weber, is that most cars currently don't really care how much electricity they use, because modern car engines are powerful enough to supply excess juice. With the Volt, excess power draws directly translate to fewer miles driven between charges. It's not simply enough, Boniface said, to ensure that all the parts are power efficient—they have to also interact in ways that keep power use down. With current technology, he said, "an electric car is easy," but getting all its parts to play nicely together is not. He estimated that about 75 percent of the hours being put in at this point is focused on the software needed to do so.

Most of that software will work behind the scenes, but there's one major power drain that's directly under the user's control: heating and air conditioning. The Volt will actually provide two layers of control to the user. Not only can they set the basic parameters—heat or cool, and how quickly—but they'll have a separate "eco functionality" control that indicates how willing they are to sacrifice charge to get there. If someone's primary goal in driving the Volt is to not run the gasoline engine, and they're willing to sweat to get there, they can let the car know that that's a priority, and the electronics will lower the performance of the air conditioner accordingly. 

Getting a charge out of the Volt 

If all goes according to plan, the battery will mostly be drawing charge from standard electric power outlets. The higher quality and higher voltage power in Europe will take it from drained to full in only three hours; it'll take eight here in the US. The Volt has a slide-away bit of detailing near the driver's door that reveals a receptacle. Drivers just have to carry a cord that ends in a plug appropriate for their local electric supply.

GM showed figures that indicated charging the Volt would have a power drain in the same neighborhood as an electric water heater or a fridge/freezer. Even putting a million Volts on the road wouldn't add more than one percent to the load on the (somewhat fragile) US electric grid. At typical off-peak rates, a full charge would cost in the area of 80¢, working out to about $10 a month. They estimate a savings of about $1,500 a year over a gasoline powered car. 

The battery compartment separates the left and right seats

The weakest part of GM's argument is probably related to the availability of outlets to plug the thing into. As other reporters noted, the early adopters of technology like this are likely to be urban and suburban dwellers, and many of them park their cars in garages or shared parking areas where there simply aren't outlets, much less ones that would charge the electricity used to the right person. The GM reps suggested that their Onstar system already can associate cars with billing, but it's not clear that really solves the problem. Of course, at 80¢ a day, it's not clear that there really is much of a problem here.

In general, it seems that GM is currently in talks with major grid companies about possible solutions, but the company is relying on the Volt to drive solutions, rather than ensuring that solutions are available when it hits the market. It's not unreasonable, but, at the same time, I'm pretty sure that it rules out anyone living in my building as a potential Volt owner, as nobody's going to be anxious to leave an unattended power outlet in the indoor garage here—much less either of the two outdoor lots.

Don’t forget it’s a car

With all the focus on technology, it's easy to forget that the Volt actually has to function as a car and, more specifically, a car that people would want to own and drive. GM didn't make the job easy on itself by showing a concept design that was completely unworkable, having the wide frame and huge wheels of an SUV with a sleek, low-slung body dropped on top of them. People, including some of the press at the event, were expecting a radical departure, befitting something the company was betting its future on.

They didn't get it. As the pictures make clear, the Volt is a modern-looking design, but very much a conventional car. GM's focus groups told them the same things that the first hybrids on the market told Honda and Toyota: people want something that's noticeably different (as in the Prius), but not so outlandish that it looks like a reinvention of the car (see the Honda Insight). So, GM started with a rough design based on what people find appealing in cars, such as a low front, wide stance, and raised tail.

Both the wheel and spoiler are designed to
add to the Volt's range

It then got ruthless with the aerodynamics, knowing that every 10 units in the scale it was using for drag meant a half-mile of range or 10kg of weight it could use elsewhere. Tiny details counted, as a raised lip on the rear spoiler wound up being worth a quarter mile. That doesn't mean that style was completely sacrificed. Aerodynamically, it would have been best to make the side what Boniface called a "flat slab," but enough was saved elsewhere to allow the wheel wells to bulge slightly out. Incidentally, those wells house a tire specifically designed for the Volt, one optimized for rolling resistance. In that regard, it does 15 percent better than what's already being marketed as an "eco tire."

The interior is also an evolution of existing cars. The gauges and meters are displayed on a single LCD over the steering wheel, while a second touch screen LCD dominates the center console and handles things like GPS, entertainment, and environmental controls. The controls below it are simply touch-sensitive hardware—there are no actual dials or levers. The presence of the battery clearly separates the left and right seats like a vertically-exaggerated driveshaft; GM has raised this even further in order to place cupholders and storage in it.

The instrument panel and gear shift are
designed to be modern yet familiar

I asked Boniface about the gear shift that appears in the Volt, given that the electric motor drives the wheels directly. He said they toyed around with a forward/reverse switch, but ditched it for two reasons, the first being simply that they didn't want to make the driving experience unfamiliar. The second, however, is they thought people would find neutral useful, and they put in a stop-and-go traffic gear that makes the acceleration less sensitive and directs more of the braking to the generator.

But the dominating impression of the interior I came away with is "cramped." I'm well over six feet tall and currently drive a car (a Toyota Matrix) with huge amounts of head room, so I asked some of the other reporters for their impression; people both shorter and slimmer than I am felt the same way. One woman who was roughly my height sat in the back seat and said she felt that closing the hatch would have slammed it onto the top of her head.

Can the Volt future-proof GM?

GM has gotten a lot of things right with the Volt. It is fundamentally different than a hybrid, and may (if it comes to market in time) allow them to leapfrog a lot of their competition—electric motors, from everything I've read, really do give a great driving experience. It really looks to be the first electric car that functions well as a car—at least assuming you and all your passengers are on the short side.