Test Drive: Tesla Roadster

By Sean Carroll | August 21, 2009 11:10 am

Here at Discover Media LLC, we are dedicated to bringing you news of the cutting-edge technology that will change your life. So we dispatched our Cosmic Variance automotive editor (me) to test-drive the car of the future: the all-electric Tesla Roadster. (No real secret actually; I have a friend who owns the car.) Thus, yesterday’s picture.

Fancy titles notwithstanding, I’m by no means a true car nut, so I can’t offer the insider perspective of a real expert. My take is that of an ordinary person who just had a chance to drive an exotic car through the hills north of San Francisco. After considering the experience carefully, my considered judgment could be expressed as follows: pretty frikkin’ awesome.

tesla-roadster.jpg Let’s get some basics out of the way: the Tesla, with a body based on the Lotus Elise, is a tiny car — a two-seater with a trunk that can at best be described as decorative. And it’s low to the ground; climbing inside is a bit of a process for the uninitiated. Inside, the electronics are all state-of-the-art (as one might expect), but the Roadster is not a cushy luxury car. It’s not uncomfortable, but you’re not being coddled by piles of plush leather. Removing the convertible soft top is a matter of unsnapping and stowing by hand; takes just a few seconds, but we’re not talking about a top-of-the-line Mercedes where there are separate buttons to stow the top, clean your sunglasses, and freshen your martini. The Tesla experience is about the driving; fripperies are for future incarnations.

So you sit down, turn the key to start the engine, and: nothing. That’s to be expected, and should be familiar to anyone who has driven a Prius or other hybrid. The electric motor doesn’t need to be turning when the car isn’t moving, so turning the vehicle on just means some lights come on. Spooky at first, but you get used to it.

Actually pulling out into the road and driving is a different story. There are basically three things that distinguish the Tesla driving experience from that of your typical Ford Taurus or what have you. First, as you may have heard, the Tesla doesn’t believe in a little thing called a “transmission.” Technically, there is a transmission, but really it’s just a reduction mechanism that translates a certain number of motor revolutions to a certain fixed number of tire revolutions — there are no gears, so there is no shifting, manual or otherwise. The original plans called for a two-speed transmission, but it proved unreliable, so they said screw it, let’s just have one gear. As a result, the rate at which the motor is turning is directly proportional to the rate at which your car is moving. That includes reverse; when you’re backing up, the motor is spinning in the opposite sense from when you’re moving forward. In a conventional car with an automatic transmission, there can be a bit of a delay between when you push down on the accelerator and when you actually accelerate, as the car tries to decide what gear it should be in. No such hesitation in the Tesla.

The second thing, which you may not have heard, is that there is no power steering. I don’t know whether that was a matter of cutting down on weight, or whether it was just thought that power steering wouldn’t be keeping it real. But despite its diminutive profile, the Tesla is not a light car, coming in at about 2,700 pounds — a third of that in the form of batteries. (The Elise, in comparison, is only about 2,000 pounds; but a Mazda Miata comes in at 2,500 pounds and a BMW Z4 at 3,200 pounds, so the Tesla isn’t unreasonable.) To those of us who have gotten used to having the car practically steer for us, the Tesla is a bit of an adjustment. But the adjustment happens quickly, and it’s very much in keeping with the sporty nature of the car — you’re here for performance, not coddling.

The single gear and the lack of power steering combine to create an effect I hadn’t really anticipated before the drive: a visceral connection between the driver and the ground. It’s hard to imagine a driving experience that is on the one hand that fast, and on the other hand features so little mediation between what you do at the controls and how the car responds. The engine turns, and the car zips along, at precisely the speed you tell it to, no more, no less; and the wheels turn at an angle precisely proportional to the attitude of the steering wheel in your hands. You are in control.

And — to come to the third crucial distinguishing feature — you’re in control of a lot. This puppy is fast. By which I do not mean, as physics training might lead you to suspect, that it travels at a high velocity. In fact the car is electronically regulated so that its maximum speed is 125 miles per hour (and I didn’t approach the limit, don’t worry). That’s fine, because despite the emphasis on sportiness, this is a car that is meant to be driven on actual roads with actual traffic laws. But because state legislatures aren’t required to pass any calculus exams, our rules of the road feature speed limits, but not acceleration limits. And it’s really acceleration that gives a car a feeling of being “fast”; when you push down on the accelerator, how quickly do you speed up?

In the Tesla, the answer is: as quickly as you could possibly want to accelerate outside a racetrack. The technical numbers tell us that the Roadster goes from 0 to 60 in 3.9 seconds. (A Porsche Boxter does 0-60 in about 5 seconds.) All I can say is, it’s incredibly, breathtakingly fast. Punch it, it’s gone. Only after driving this car did it occur to me that maybe there should be acceleration limits written into the traffic laws; being able to accelerate faster than this strikes me as very plausibly dangerous. Once you adjust to the parameters of the vehicle, the combination of the incredible power and the unmediated response to your actions yields a driving experience that is pretty darn breathtaking.

There are a couple of other idiosyncrasies to remind you that this is not your father’s Oldsmobile. Although the Tesla is utterly silent while standing still, it definitely does make noise while moving. Not very much noise, but what comes to mind is less a Ferrari and more a muffled jet engine. I presume this is because the engine is turning notably faster (perhaps 7,000 RPM at highway speeds, I didn’t check carefully) than in an ordinary car. The other thing is the regenerative powertrain. When you take your foot off the accelerator, the car slows down perceptibly — it’s taking some of your kinetic energy and using it to recharge the batteries. So you don’t need to put on the brakes while going downhill. (Sadi Carnot would have something to say about this, but don’t worry — you’re still creating some entropy, just achieving something closer to theoretically maximal efficiency.)

In other words: the Tesla Roadster is an extremely fun car. But is it practical?

Well, it’s not practical for most of us to actually buy — the sticker price is on the order of $120,000. And you’re not going to take four kids and a dog to the soccer game. Nor are you going to take a road trip across the country; under ordinary driving conditions, the Tesla gets about 200 miles between charges.

But all that is okay. The vast majority of driving is not done on long hauls or with a car packed full of people; it’s done by a single person on relatively short jaunts. For those purposes — commuting to work, running errands, going to meet friends — something like the Roadster is just about perfect. There’s no reason to lug around two tons of car with room for six when there’s only a driver inside. Very few people would want a Tesla as their only car, but if they had two cars, it would be the one they were driving most of the time. And if you can afford to buy the thing in the first place, you can afford another car.

More importantly, in its current incarnation the Tesla is not about practicality; it’s a proof of concept. Electric cars have long suffered under the image of being under-powered and super-short range, needing to return home every 50 miles for a lengthy recharge. The Tesla blows those stereotypes out of the water, and that was the idea. Here is a car that is environmentally conscious, but is no sacrifice once you’re behind the wheel. It proves that an electric car can have a decent range and be easily recharged. And let’s face it — it’s hot.

Not that it is quite plug-and-play. The Tesla is powered by an array of about 7,000 lithium-ion batteries, not too different from what you have in your laptop computer (but with special care taken to ensure long life, no overheating, and no explosions). You could, in principle, plug the recharger into an ordinary 110 volt outlet already in your home; problem is, a complete recharge would take about 30 hours. (If you’re only driving about 30 miles a day, you wouldn’t need anywhere near a complete recharge.) If you’ve gone this far, however, you probably want to install a 220-volt receptacle; most homes are already wired for the increased voltage, but you have to spend a hundred bucks to install the appropriate unit. Now the car can be fully recharged in about 3 1/2 hours. In other words: come home, plug it in overnight, drive away the next morning.

Of course, even if we all were driving Teslas, the world would not suddenly transform into a green utopia. That electricity has to come from somewhere, and right now it mostly comes from burning dirty fossil fuels like coal. I’ve read that, under the current setup, driving a mile in a Tesla is just a little bit better in terms of total carbon emissions than driving in an ordinary car; you’re using less energy, but it’s coming from a dirtier source.

The system is going to have to change. We can’t keep burning petroleum in our individual cars, nor can we keep burning coal to get our electricity. The point is that it’s fairly easy to see how to get electricity form sources other than coal — we’ll need a portfolio of nuclear, solar, wind, etc. But the cars are going to have to go electric, there’s little question about that. (Believe Steve Chu if you don’t believe me.) A major challenge is going to be upgrading the electrical-power transmission grid; T. Boone Pickens recently had to abandon an ambitious plan to build a giant wind farm in Texas, after he realized that he didn’t have the resources to carry the power to the people who actually wanted to use it. But doing that upgrade is not optional, and it’s a matter of willpower rather than technological breakthrough.

Tesla obviously isn’t the only company that’s caught on to the promise of electric cars, although the Roadster currently blows away the competition in terms of speed, acceleration, and range. The much-hyped Chevy Volt from GM is actually a plug-in hybrid, which includes an internal combustion engine to help the electric motor along when you want to go fast or far. That may be the wave of the near future, but I suspect that 100% electric is the medium-term solution. (Until we all have personal jetpacks, or the Singularity arrives.)

tesla_model_s_official_new-thumb.jpg Still, it would be nice to have a car more people could afford, and which could hold a couple of friends and/or offspring as well as the driver and a single lucky passenger. Behold: the Tesla Model S. Scheduled for first delivery in late 2011, this will be a true four-dour sedan, with a range of up to 300 miles. Still not cheap; estimated cost is around $60,000. But that’s completely competitive with executive-class sedans from Mercedes, BMW, or Audi. The Model S won’t put an electric car in everyone’s garage, but it will help “normalize” the idea of owning one — you’ll start seeing them on the streets in increasing numbers. And after that, there are hopes to offer another model for less than $30,000. Still not cheap, but getting there.

The future belongs to electricity. The good news is, it’s a pretty sexy future.

CATEGORIZED UNDER: Technology
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Cosmic Variance

Random samplings from a universe of ideas.

About Sean Carroll

Sean Carroll is a Senior Research Associate in the Department of Physics at the California Institute of Technology. His research interests include theoretical aspects of cosmology, field theory, and gravitation. His most recent book is The Particle at the End of the Universe, about the Large Hadron Collider and the search for the Higgs boson. Here are some of his favorite blog posts, home page, and email: carroll [at] cosmicvariance.com .

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