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Innovation

Designing the Volt: Six ways it's different from your car

Designing a vehicle for an electric powertrain requires different considerations than one using an internal combustion engine. GM interior designer David Lyon takes us through the paces using the Chevrolet Volt.
Written by Andrew Nusca, Contributor

When I took the Chevrolet Volt for a test drive last November, I had the pleasure of meeting several (rather giddy) members of GM's design team.

Before I hopped in, they took me on a brief walk-around of the car, pointing out several ways that the Volt -- which for all intents and purposes is an electric vehicle, though it has a small gasoline engine as a long-distance safety net -- is a different kind of design challenge than a conventional gas-powered car.

The hump in the middle of the car, between the seats? It's not the transmission, it's the electric battery.

The grille? Almost completely solid, because an EV's powerplant doesn't need cooling.

I always wanted to know more. Yesterday afternoon, I spoke with executive director of interior design Dave Lyon at his office at the GM Design Center in Warren, Mich. to do just that.

What ensued: lots of shop talk and a deep dive into what makes designing for an EV so different.

Reason No. 1: Aerodynamics.

"In a lot of ways, when we're developing any car, we're trying to balance interior roominess versus styling and aerodynamics. There's a push and pull. We want as much space as possible but still look incredibly desirable.

"Aerodynamics matter a lot. We try to balance it so that they're not a real deterrent to fuel economy, but we do have some cars in the portfolio -- the Volt is one of them -- where aerodynamics come first. It's not that different from when we work on a Corvette. It posts nice numbers on the track. You don't want to be in one that isn't optimized in the [wind] tunnel first, or you may find yourself shiny side-down somewhere on the side of the road.

"On the Volt, we knew that once you're on the highway, aerodynamics is actually much more important than weight when it comes to fuel economy. We gave ourselves very aggressive aero targets. If we didn't achieve those targets, the 40 miles [per gallon figure] might be 39 or 38. Those aren't actually the [Volt's mileage] numbers -- I went to art school! -- but we'd lose bragging rights [if we didn't focus on aerodynamics]. That's the range people are looking for. People want to plug it in and not have to use the gas.

"With the new CAFE standards, the more aggressive aero targets are the way of the future. We want to make sure each car looks different. But with the Volt, that windswept look is part of why you're buying the car. It was kind of fun.

"It's like the Corvette. They're both high-performance vehicles in very different ways. The Volt is the Corvette of efficiency. In the Corvette we have a G-meter to tell you the G-forces when you take a curve. On the Volt, there's an efficiency gauge that's similar to that.

"The scoops in the wheels helps get rid of the extra material. They're very low mass. The geometry of those wheels actually helps with the aerodynamics. They send air out or in as they rotate, and air going in under the car is very bad for aero."

Reason No. 2: Battery considerations.

"The T-shaped battery pack makes seating a little different. If you're sitting in the Volt, you're further away from the center line of the car than we normally do [for a gas-powered car]. You're more outboard than we normally do.

"Luxury rear-wheel drive cars are the same way. The big hump running down the middle [of the car] is usually the transmission and the driveshaft; here it's the battery.

"The batteries were shaped knowing that they were going in the center of the car. They met us halfway in the packaging. Batteries are just big bags of chemicals -- they're T-shaped because the engineers like order.

"It's only a two-seat backseat [to accommodate for the battery hump]. A fair amount of customers say it feels more exclusive to be a 2+2 rather than a bench. But we knew we would be getting early adopters; we knew there was a certain amount of tolerance for doing things differently."

Reason No. 3: A lack of automatic controls.

"The seats area is a great example [of something different]; it's an all-manual seat. You want to slide back or forward? The controls are all manual levers.

"One reason for this was mass, but the other thing was electrical draw. That draw comes out of the car's range. Volt owners are OK making that tradeoff. But they still wanted leather seats."

Reason No. 4: Rethinking heating and air conditioning.

"When you're in a regular internal combustion vehicle, you've got all the heat you'd ever want. Interior heating is easy -- if you're not heating it, you're throwing it away.

"On an electrical vehicle, there's no internal combustion motor generating heat. Heating the interior again comes out of [the car's] range.

"What's the most efficient way of heating someone? Ducts in the car, with outlets throughout the interior? We'd have to put a pretty big heater. What we found were heated leather seats are actually very effective for this purpose, because it's direct contact. In the Volt we heat the air, too, but it's a very small [contribution]."

"Within the heating and air conditioning controls, there are three settings: fan-only (the most efficient), eco-mode (you can set it to 72 degrees, but it will take its sweet time to get there) and comfort mode (it will get you there regardless of battery charge). In talking with the engineers, there are two big drivers of efficiency in EV mode: one is driving style, and the other is how much air conditioning and heating you're using.

"A lot of the interface is trying to manage the driver's behavior to improve the experience with the car. It gives advice if you go looking for it, but it doesn't give it to you if you didn't ask."

Reason No. 5: A new interface that does new things to accomplish similar tasks.

"The actual interface to the car doesn't have to be anything like what people are used to. We wanted to make sure the Volt wasn't like getting into a normal car. But there's also danger in creating a total science experiment. It's still a car, you need to be able to operate it without the manual. Someone needs to throw you the keys and you can drive it without the tutorial. What's the right amount? Other manufacturers have gotten into trouble -- lawsuits -- because [they strayed too far from expectation].

"Safe and intuitive but, also feel different. The push-start is different on a Volt, though, because you're letting the car know you're ready. You're not actually starting the motor."

On the ignition:

"We had a prototype plugin hybrid vehicle here at Design Center a few years ago. I was with a friend, and he presses the button and nothing happens. He presses again, and again. It must be dead. The operator says, "Just put it in drive." There was nothing to let us know that the car was ready.

"When you get into the Volt, we're basically leading the witness. A blue button toward the bottom of the center stack pulses with a glow. You think the next step is to press it -- it's so juicy, you can't not press it. We almost made it red, but we thought people would probably think a missile would go off.

"And when you press it, we have kind of a startup sound. That was a big deal -- should we make it sound like a Ferrari V-12? An android voice? Whatever we did, we had to remember that the owner would get tired of the irony after six months. So we picked something neutral. So when you press the start-stop button, it wakes the system and lets it know that it's ready to go. But we've created audio and visual cues to let you know that."

On the shifter:

"When we got to the shifter -- well, there are a lot of electronic shifters out there: knobs, dials, paddles. In this case, we just went with a very traditional system, but we took it so far forward it's actually a part of the center stack. We don't have a lot of depth to the console because there are batteries back there. Once you push that button and hear the cues, without thinking you can grab that shifter and drop it right into drive or reverse.

"Space considerations were also an issue. We pushed it up so there's a nice amount of space there. We wanted it to make it so, when parked, there was almost no shifter. We also wanted to make room for more storage [between the two front seats]."

On the display panel:

"We looked at traditional gauges, and they just didn't look right in an electric car. We did some research and there are two kinds of people: people who want just-the-facts-and-don't-bother-me, and people who want more information. We can scale the level of [displayed] information up and down.

"For example, when I took home the Volt over Christmas break, I thought I'd never use the floating green orb that tells you how efficiently you're driving. But that darn little green efficiency ball gets to you! You do change your driving behavior."

Reason No. 6: A front grille that's mostly solid.

"When you look at the [Volt's] front end, we don't have the cooling requirements of a traditional car. We could put anything on the front of this car.

"But if you put a traditional grille on the front end of this, it won't feel like a car of the future. It has the graphic but it's been filled in and flushed out, which is good for aero. It still has that [visual] connection. It lets in a little bit of air around the edges, but that's all it needs -- it still has that small internal combustion engine underneath.

"We found in the air tunnel that sometimes you need to add holes in the upper grille to let out air pressure. Air goes into the radiator and fills the engine compartment. If it gets trapped, it starts spilling out and creating unwanted aerodynamic currents. You never really know what you need until you're in the wind tunnel."

Also: Designing away from EV expectations.

"Some of the things that make the Volt unique was just the fact that we weren't always perfectly efficient on some of these things. If you really want the most efficient [vehicle] layout, the resultant car is probably the first-gen Toyota Prius. It's an awkward animal. Tiny wheels, minivan-like doors, a tall roof.

"When we look at a lot of manufacturers' approach to doing these vehicles, the first thing they do is put the smallest wheel and tire that's safe and start with a small car and blow the interior out as big as possible. One side of my brain thinks that makes sense, the other side thinks it's still going to be an expensive piece of hardware and you want something that looks good. I don't know who is so self-actualized that they don't care how they look.

"We went through a lot of trouble to make proportions appealing. Keeping it low and sleek is kind of nice. We could have made the roof higher at the expense of aero.

"The biggest thing about the Volt is how big the tires are, sitting nice and snug in the well. On EVs, the widest part of the car is usually up in the glass; they look tippy. We wanted a nice, wide stance. Yes, there's some extra math and we worked a lot with engineering to optimize the geometry -- but at that size, there is no lighter wheel. We wanted a luxury/sport side-view.

"The Volt is a 'halo vehicle' for Chevy. If it doesn't have Chevyness to it, you don't have the [visual] connection. Not everybody who goes in for a Volt comes out with one, but you might come out with a Cruze Eco. I don't expect those guys to flash headlights at each other on the road, but they have some connection. 'Yeah, that's the company that makes the Volt.'

"There are more things we're working on now, but I can't tell you about them yet. The Volt was a really fun project and made you think about every element and why you do it in the first place. It kind of changes your approach to every project after that."

Photos: General Motors

This post was originally published on Smartplanet.com

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