The Roadster showed Tesla Motors can design a top-notch electric drivetrain. The Model S showed it can design a gorgeous car. Building the S is another story, of course, so now the Silicon Valley upstart wants to show it knows a little something about engineering.
Elon Musk’s upstart automaker rolls into the Detroit auto show with an “alpha build” of the Model S sedan. The term is a nod to Musk’s insistence that Tesla Motors is more Silicon Valley than Detroit. That conceit aside, Tesla is talking about a hand-built pre-production car pretty close to what it keeps saying we’ll see in driveways sometime next year. It’s a key milestone for the company and the car that will make or break its future, another sign that Musk just might pull this off.
Tesla has at least three alphas, each assembled at its HQ in Palo Alto, California, using bodies built by a supplier in Michigan. It will use them to test components and subsystems and track test the car in the months to come. At some point — Tesla won’t say exactly when — it will transition to “beta builds,” production-intent vehicles built entirely at its factory in Fremont, California. Those cars will be used for system integration, testing and, eventually, federal crash testing and certification.
The car we’ll see on the floor of Cobo Hall will be “expanded” like an exploded-view diagram so people can get a close look at the nuts and bolts of its construction. The version we saw during a sneak peek this week at Tesla HQ suggests the car’s beauty is more than skin deep.
Musk has made a huge bet with the Model S, the sexy seven-passenger electric sedan upon which the company’s future rests. The car promises all the luxury of a BMW 7-Series, and the company claims a range of up to 300 miles. The U.S. Department of Energy was impressed enough to loan Tesla $465 million to build the S.
Tesla showed us a body-in-white, an industry term for a painted unibody shell without an interior, drivetrain or other components. It’s an impressive mix of cast, extruded and sheet aluminum with smattering of boron steel and dual-phase steel. The front and rear shock towers along with various suspension and crash-safety components are cast; the front, side and rear rails are extruded. Tesla wouldn’t allow us to take any photos (the pics show earlier prototypes) and refused to provide any, saying it’s still filing patents. It did, however, release three videos shown below.
Chief engineer Peter Rawlinson, a veteran of Jaguar, Lotus and Corus Engineering, says about 98 percent of the unibody by weight is aluminum. Aluminum is expensive and tricky to work with, but it is light — a key consideration for an electric vehicle because weight, like aerodynamics, has a huge impact on range.
With that in mind, Tesla is shooting for a curb weight around 4,000 pounds. That’s on par with the Audi A8, another all-aluminum car generally believed to be a benchmark for the S. The company also promises “best in class” aerodynamics from a body designed in-house by Franz Von Holzhausen (who’s work includes the Pontiac Solstice and the wild Mazda Furai concept) and tweaked by former Formula 1 aerodynamicists Robert Palin (Williams F1) and Shaun Johnson (Ferrari).
The Model S, when it was unveiled in March, 2009. Photo: Jim Merithew / Wired.com
Tesla’s keeping mum on the size of the battery pack, but the Roadster has a 53 kilowatt-hour unit. Expect the S to be in the same ballpark. Although the S will be considerably heavier than the Roadster, Tesla says the two cars will use the same amount of energy to cover a given distance. It attributes that to the sedan’s superior aerodynamic and drivetrain efficiency.
The company also has said it is getting more performance out of its packs. Kurt Kelty, director of power storage technologies, says the pack in the Roadster has an energy density of 120 watt-hours per kilogram; that rose to more than 135 in the packs Tesla designed for the Smart Electric Drive prototypes.
Whereas the pack in the Roadster is a 950-pound rectangle directly behind the seats, the pack in the S is a structural element integrated into the unibody. It measures roughly 5 feet by 8 feet and fits between the axles under the floor between the door sills. Rawlinson said that gives the body remarkable torsional rigidity and “unparalleled protection in side-impact collisions.”
“The battery pack does much more than contain the (battery) cells,” he said. “It contributes to the car’s handling, safety and packaging.”
The car rides on a suspension designed by Huibert Mees, who worked on the Ford GT, and tuned by Lotus alum Malcolm Burgess. (Test driver Graham Sutherland also came from Lotus.) Although Tesla has partnerships with Mercedes-Benz and Toyota and could have simply raided those two companies’ parts bins, it chose to design its own suspension system. The front uses double control arms; the rear is a multilink setup. All of the major components — the control arms, steering knuckles, bushings and the like — were designed in-house and made of cast and extruded aluminum.
“We can put everything exactly where we want it and optimize it for our architecture,” says engineering manager Roger Evans, who came to Tesla from Ford Motor Co.
Other components come from big-name suppliers like Brembo, Bosch and Bilstein.
The rear suspension is packaged along with the liquid-cooled AC motor, the transmission and the power electronics module; it all fits between the rear wheels in an aluminum subframe. It is, like everything else, remarkably tidy.
“I’m very pleased by how this car has been packaged,” Rawlinson said. “It’s beautifully packaged. Every millimeter counts.”
Because all of the major components are under the car, the S will be spacious. It will include a trunk where the engine is located in a conventional car and an optional rear-facing third-row jumpseat, giving the car room for seven people. All told the S will offer 29 cubic feet of cargo space. When Tesla unveiled the car almost two years ago, Musk boasted it could carry a mountain bike, a surfboard and a flat-screen TV simultaneously, as if anyone would do that.
Practicality and cavernous cargo capacity aside, Rawlinson promises the S will be “a driver’s car.” He boasts that it will offer better handling and refinement than anything else in its class — a tall order, given the S will compete with top-tier cars from Mercedes-Benz, BMW, Audi and Lexus.
How the car will fare against that kind of competition remains to be seen. And before anyone can drive it, Tesla has to build it. Musk remains confident the S is on track for delivery in 2012 and has said, “there are no outstanding engineering challenges left.” That may be so, but Tesla still has to finish the car, tool the factory, train the workforce…
There is skepticism Tesla will meet its goal. It isn’t an issue of talent or money. It’s a matter of time. It doesn’t matter how skilled the engineers are, how effective the management is. There are only so many hours in a day, and so many days in a month.
And then there’s the legitimate question of how Tesla will sell what amounts to an electric BMW 7-Series (which starts at $70,650 and rises quickly) for a base price of $57,400 and turn a profit doing so. Tesla says it will rely upon vertical integration, developing as much of the car in-house as possible and “forcing suppliers to meet cost targets.”
“It will be a challenge,” says Jim Dunlay, VP of powertrain engineering. “But it’s a challenge that has been part of the process from the beginning. It’s aggressive, I know. But we expect to be a profitable company selling the Model S.”
Time will tell, and the clock is ticking.
Main photo: Jim Merithew / Wired.com. The Model S at the Tesla factory. Videos: Tesla Motors
Peter Video Blog #1 from Tesla Motors on Vimeo.
Peter Video Blog #2 from Tesla Motors on Vimeo.
Peter Video Blog #3 from Tesla Motors on Vimeo.