NEW AND FUTURE CARS: 2008 Tesla Roadster

March 11, 2008
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0803 13 Z+2008 Tesla Roadster+front Three Quarter View
The future of the automobile comes into sharp focus as I shiver on the shoulder of a damp road in Northern California, waiting for technical editor Don Sherman to make his first 0-to-60-mph pass in a Tesla Roadster - a preproduction version of the svelte, $100,000 electric two-seater powered by 6831 laptop-computer batteries and the collective enthusiasm of an intrepid band of Silicon Valley engineers and green dreamers the world over.
Sherman puts the car in gear and mashes both the brake and accelerator pedals. Unlike conventional reciprocating engines, electric motors make maximum torque at zero rpm. With 211 lb-ft straining against the firmly clamped brake rotors, the Tesla emits a weird mechanical groan, a cross between a mortally wounded ship sinking to the bottom of the ocean and the prefight keening of a kung fu master in a cheesy chop-socky flick.
When Sherman releases the brake, the gracefully rounded rear end of the Tesla squats and the fat rear tires spin on the slick pavement. The car leaves the line sideways, launching like an Indy car slithering out of the pits. Then I hear another unexpected sound - the puny squeal of the horn, which Sherman is squeezing inadvertently as he slaps on an armful of opposite lock. ("I was hanging on for dear life," he reported later.) Finally, the tires hook up, and Sherman rockets past 60 mph - and past 100 mph, for good measure. And as he dematerializes into the fog, I find myself thinking, "Sweet!"
0803 14 Z+2008 Tesla Roadster+rear View
The Tesla Roadster isn't going to save the planet. It's not going to redefine the automobile. The earth won't spin off its axis if and when the first cars come off the production line as scheduled later this year. I mean, we're talking about a projected 2008 model year run of 600 units. Toyota cranks out that many Corollas in a morning. So this isn't an electric Ford Model T. It's more like a glorified science project. A tree-hugger's wet dream. A geeky curiosity to display next to the solar-powered toothbrush and organic Twinkies, right?
Wrong. As wrong as a Toyota Prius on a Formula 1 grid. Or Ed Begley, Jr., channeling Steve McQueen in a remake of Le Mans.
Not only is the Tesla the first genuinely eco-friendly vehicle to deserve a spot in any self-respecting car guy's fantasy garage, but it's also the first car to make a plausible case for all-electric personal transportation in the not-too-distant future. Oh, sure, the haters will tell you that the Tesla Roadster is powered mostly by hype, that nothing with a top speed of 125 mph deserves to be called a supercar, that it's merely a high-voltage version of the Lotus Elise built by an underfunded start-up masquerading as a grown-up car company.
So here are a few things you ought to know about the Tesla: With the equivalent of 248 hp and 211 lb-ft of instantly available torque, the car we tested surged to 60 mph in 4.7 seconds - in damp conditions. Al-though it is, in fact, based on the Elise, the highly modified Tesla is more refined in every way. And despite the addition of the 1000-pound battery pack, the Roadster is everything a sports car ought to be - agile, responsive to driver inputs, and rewarding at speed.
0803 15 Z+2008 Tesla Roadster+interior View
But best of all, it's right here, right now. This isn't a piece of Silicon Valley vaporware or a show car made out of balsa wood and duct tape. Sherman and I flogged a pair of Teslas - prototypes 19 and 20 - around the twisty roads between San Jose and San Francisco for the better part of a day, and neither car missed a beat. The experience made a believer out of me. And I'm convinced that it'll do the same for any car enthusiast who gets a chance to drive one.
Does this mean you ought to start shorting stock in companies selling conventional cars? Hardly. The Tesla's range is limited to about 220 miles - less if you plan to play hooligan. The battery packs are outrageously expensive, and longevity is an open question. Starting at $98,950, the Roadster is obviously too pricey to change the world. And while Tesla is developing a sedan to compete with the BMW 5-series and the Mercedes-Benz E-class, the company isn't merely a minnow by automotive standards. It's an amoeba.
"Getting to this point has been a remarkable achievement," says auto analyst and consultant John Casesa. "But the viability of the company has a lot to do with economies of scale, brand development, and distribution networks. And assuming that their technology doesn't turn out to be completely proprietary, then they're going to come up against a lot of the traditional automobile companies. In addition to maintaining its intellectual and technological leadership, the company is going to face some large industrial challenges."
0803 18 Z+2008 Tesla Roadster+trunk
Electric cars have been coming off the drawing boards - and dying in the marketplace - for more than a century. In fact, most of the conference rooms in Tesla's offices in San Carlos are named after failed electric car companies. (Irony or hubris? You make the call.) In recent years, of course, the most notorious failure was General Motors' EV1, which was killed not, as filmmaker Chris Paine and conspiracy theorists maintain, by a greedy, shortsighted car company but by batteries - first lead-acid and then nickel-metal-hydride - that compromised its range. But the development of more potent lithium-ion batteries, commercially available since the early 1990s, offered new hope to electric car devotees.
Tesla Motors was founded in 2003 by Silicon Valley entrepreneurs Martin Eberhard and Marc Tarpenning. After striking out with venture capitalists, they found a sugar daddy in multi-millionaire Elon Musk, cofounder of PayPal and CEO of the space exploration firm SpaceX. (To date, he's provided $37 million of the $105 million raised by the company.) Their first major hire was chief technical officer JB Straubel, a young engineer who'd independently started developing an electric vehicle powered by thousands of lithium-ion laptop batteries.
0803 17 Z+2008 Tesla Roadster+interior View
Tesla is in business not to make a statement but to make money. So instead of pandering to hair-shirt environmentalists with a bland, anemic, painfully practical piece of minimalist transportation - what the company calls "a punishment car" - they opted for an aspirational vehicle designed to be an object of desire. To speed development, Tesla based the Roadster on the Elise and hired Lotus to build it at its plant in Hethel, England. Inevitably, the Roadster looks a lot like an Elise. But Musk gets irritated when I suggest that the Tesla is just a glorified kit car. "Only ten percent of the parts come from Lotus," he insists. The exterior design is more conventionally handsome than the insectlike Lotus. The chassis is two inches longer and stouter, primarily to accommodate the battery pack, and the doorsills are lower to make it easier - "easier" being a relative term - to get into and out of the car. Although still tiny and light on amenities, the cockpit is roomier and better-appointed than a Lotus, with leather upholstery and a carbon-fiber center console replacing the molded plastic found in the Elise.
After levering myself inside and wedging into the driver's seat, I start the car. (Traditional terms such as "crank the ignition" and "bury the throttle" don't apply.) A Technicolor display of warning lights briefly illuminates the screen. Then . . . nothing. No sound. No vibration. No signs of life whatsoever. Very spooky.
"Is it on?" I ask Darryl Siry, Tesla's vice president of sales, marketing, and service, who's riding shotgun.
"Just put it in gear," he tells me.
Getting into gear - literally - has been Tesla's biggest headache. The electric motor is torquey enough to get by with a single-speed transmission, but a one-gear-for-all approach won't produce the sort of gaudy 0-to-60-mph numbers that cause enthusiasts to drool. So early on, Tesla opted for a two-speed transmission, which posed a vexing engineering challenge when mated to an engine redlined at 13,000 rpm. The huge gap between ratios has created an intractable problem, and Tesla is already working with its third gearbox vendor.
0803 20 Z+2008 Tesla Roadster+front Three Quarter View
Unfortunately, the car I'm driving (as opposed to the car Sherman tested) is fitted with an old transmission, so first gear isn't an option. As I ease out of the parking lot, I get an unmistakable golf-cart vibe. Not good, I think. Who the hell wants to pay $100,000 to feel like they're scooting across a fairway at Leisure World? But when I put the hammer down, the Roadster leaps forward. I wait for the motor to run out of steam so that I have to grab another gear. But it just keeps on pulling and pulling and pulling, feeling more like a jet doing a takeoff roll than a dragster doing a quarter mile.
The other big surprise is the sound. I'd expected the car to be silent. And sure enough, it's quiet enough that I can make out squeaks and rattles as the chassis flexes. But under power, I also hear the electric motor, and the whine gets pretty annoying at elevated rpm. "We had to ask ourselves, what noise should the car make?" says Malcolm Powell, VP of vehicle integration. Even if Tesla could fake it, the canvas-ripping shriek of a Ferrari V-12 wouldn't make sense for an electric car. Who knows? A generation from now, the high-pitched drone of an electric motor at redline may be music to the ears of car enthusiasts.
Not this one, however. And at the risk of sounding like an old fogy, I have to admit that I'm nonplussed by the one-speed transmission. Intellectually, I understand that it's easier than a conventional multispeed job. But I like shifting gears. Blipping the throttle on downshifts and heel-and-toeing under braking are two acts that connect us to our cars and enhance the driving experience. Maybe this won't matter to kids who grew up playing Gran Turismo on their PlayStations and watching in-car video from paddleshift F1 cars. But old-school sports car aficionados ought to be forewarned.
0803 19 Z+2008 Tesla Roadster And Lotus Elise+head To Head
On the other hand, my fears that the weight of the massive battery pack would compromise the character of the car turn out to be unfounded. At 2700 pounds, the Tesla is one-third heavier than the Lotus, and it lacks the Elise's feral ability to claw down to apexes. But the unassisted steering is nicely weighted and gratifyingly direct, and the car corners with the aplomb of an authentic sports car. Granted, the ride-and-handling engineers have dialed a fair amount of understeer into the suspension, but with 65 percent of the weight at the rear and no stability control, this probably isn't a bad idea. Light as it is, the car stops reasonably well (and charges the battery during braking).
But for all of its sporty characteristics, the Roadster is by no stretch of the imagination a track-day car. In fact, the air-cooled motor and power electronics will quickly overheat and lose power if the car is used for this purpose. Unlike the Elise, which was created to replicate the Schuey-does-Silverstone experience, the Tesla is tuned for a grand touring ride, and the compliant springs-bars-and-dampers package means that it could be driven comfortably for hundreds of miles at a time - except, alas, that the batteries would run out of juice before you got nearly that far.
0803 16 Z+2008 Tesla Roadster+charging Plug
Tesla claims an anticipated range of 220 miles. But that is very much a best-case scenario. According to a digital readout to the left of the steering wheel, the charge plummets each time I nail the accelerator for an extended stretch. If you plan to use the Roadster to see how close you can come to getting your license revoked, then don't expect more than 180 miles of primo performance. Of course, if worst comes to worst, you can score an emergency refill - with the optional mobile charge kit - by plugging into a three-prong household socket. The quickest charge takes between three and three-and-a-half hours when connected to a 70-amp, 240-volt circuit.
Gearbox woes notwithstanding, batteries remain the biggest technical question mark about the Tesla. At the moment, nobody knows how long the battery pack will last, and replacement costs - currently in the neighborhood of $20,000 - are bound to be expensive even if, as expected, prices drop dramatically. Service is another thorny issue. History suggests that there will be plenty of squawks with a brand-new boutique car, especially one incorporating so much new technology, yet Tesla stores will be few and far between.
Thus far, Tesla has been a happy-face avatar of the brave new world of green machinery and a darling of the environmental set. (George Clooney and Matt Damon are among the A-list celebrities who've ordered Roadsters.) But this past year has brought negative publicity in the form of production delays and downgraded speed, range, and redline benchmarks. Then, in December, Eberhard was booted out of the company he'd founded. His successor as CEO, Ze'ev Drori, a semiconductor pioneer and club racer, is an intriguing choice who plays to Tesla's strengths. Still, some observers think the decision to go with a Silicon Valley icon rather than a car-industry veteran reflects a dangerous cocktail of naïveté and arrogance, and it's not hard to imagine executives in Detroit rubbing their hands with glee at the prospect of seeing this fledgling know-it-all pull a De Lorean.
The car industry is a tough business, and it has ground up and spit out companies that were much larger, more established, and better financed than Tesla. But even if Tesla turns out to be history before too long, the future is now for electric vehicles, and anybody who thinks otherwise will be convinced by a few minutes of seat time in the Roadster.
Question & Answer:
Elon Musk

Chairman of the Board, Tesla Motors
0803 21 Z+2008 Tesla Roadster+elon Musk
Why have you invested so much time and money in this project?
I'm not an alarmist. I'm not in the camp with Al Gore. But because of the amount of time it will take to change our transportation system, we have to start now. The major reason I got involved with Tesla was to drive the transition of the whole automotive industry toward electric vehicles. And if we want to be more than a niche sports car manufacturer, then we have to increase volume and lower prices. The Whitestar [a BMW 5-series, Mercedes-Benz E-class competitor] will debut early next year and get into customers' hands in as little as three years.
Will you follow the Roadster game plan and base the Whitestar on an existing vehicle?
There's an 80 to 90 percent chance it'll be all Tesla rather than a modded Lotus. Tesla unequivocally will itself be a manufacturer. There's a limit to how much you can grow by being in another car company's ecosystem. You need to take off the training wheels at a certain point. We realize that we can no more compete with Toyota than an ant can compete with an elephant. Porsche is the paradigm for us.
Why are you using thousands of laptop batteries to power the Roadster?
Because they're available. If the batteries had been designed for cars, there would have been a different solution. But they could last seven, eight, nine years. We're planning on a four- or five-year/100,000-mile warranty, and the battery replacement pack will cost a small fraction of what it costs today. The bottom-line promise we make to our customers is that we're going to be fair, and we're not going to shaft them on the battery pack.
How Does It Work?
by Don Sherman
Nikola Tesla, electricity's mad scientist, would be proud of what a clever gang of computer nerds and car geeks has wrought in his name. The Tesla Roadster is not only the first production car powered solely by lithium-ion batteries, it's also the first electric machine worthy of the passing lane.
BODY AND CHASSIS
While the Roadster's extruded aluminum spaceframe is similar in design and construction to the Lotus Elise, most structural components are specific to this car. The wheelbase is 2.0 inches longer to provide space for the Energy Storage System and additional legroom. Sill height is lower by 1.6 inches for easier entry, and bucket seats are an inch wider for improved comfort. The Roadster's overall length is greater by 6.4 inches, and its width is increased by 0.9 inch. Body panels are carbon-fiber moldings versus the Elise's fiberglass skin. While both Lotus-built cars share the same basic steering and suspension systems, the vehicles' spring, damper, and antiroll bar calibrations are tuned to suit each application.
0803 12 Z+2008 Tesla Roadster+body And Chassis
0803 22 Z+2008 Tesla Roadster+engine And Transaxle
1. MOTOR
The Tesla Roadster's 115-pound AC induction motor spins to 13,000 rpm, delivering a peak 248 hp (185 kW) at 8500 rpm. Its laminated-steel and copper-wedge rotor is supported by two sealed and permanently lubricated ceramic ball bearings. At least 205 lb-ft of torque is available from 0 to 6000 rpm. The exterior surfaces of the motor are air-cooled.
2. TRANSAXLE
The Roadster's transaxle, developed by a Tesla/Ricardo collaboration, is a dual-clutch, three-shaft, two-speed automatic. First gear is 4.20:1, second is 2.17:1, and the final-drive ratio is 3.41:1. The wet clutches are servo-operated and computer-controlled. The engineering goal of changing gears in 0.3 second had not been realized at the time of our test drive.
3. POWER ELECTRONICS MODULE
The inversion of the battery pack's DC voltage to the three-phase AC required by the motor is handled by power-switching semiconductors packed inside a "black" box that measures four feet by one foot by eight inches. The semiconductors - called Insulated Gate Bipolar Transistors (IGBTs) - were invented in 1982. Third-generation IGBTs now in use for hybrids and electric cars are fast-acting, rugged, and affordable. Recharging equipment is also contained within the black box.
4. BATTERY PACK
The Tesla Roadster's Energy Storage System mainly consists of a battery pack, a cooling system, and seventeen circuit boards. The battery array contains 6831 3.7-volt lithium-ion cells, each of which measures 2.56 inches in length by 0.71 inch in diameter (about 30 percent larger than a AA battery). A total of 69 cells connected in parallel make one brick. Nine bricks wired in series produce one sheet. Eleven sheets wired in series yield a battery pack providing a nominal 366 volts and 56 kilowatt-hours of electrical power. Propylene glycol circulated through aluminum tubing in contact with every cell keeps the battery pack's temperature within its set limits. The same AC compressor that maintains the Tesla's cockpit comfort removes heat from the battery-coolant circuit. A network of voltage, temperature, smoke, moisture, shock, and rollover sensors guard the pack so that power delivery can be interrupted in the event of a problem. Various fail-safe and limp-home modes exist so that some mobility is maintained even when recharging is temporarily prohibited. A normal recharge cycle ranges from forty hours using the 15-amp, 120-volt mobile (in-car) charger to three-and-a-half hours using a 70-amp, 240-volt home unit.

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