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Tesla's electric dream

Roadster 2.5 hits 60 mph in 3.7 seconds…with zero emissions

By Kevin Schweitzer, Special to Tribune newspapers

3:13 PM EST, November 11, 2010

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Sports cars, true high-end performance machines, are often referred to as dream machines. They wildly exceed everyday expectations, they satisfy fully, and they're unattainable in the real world.

The Tesla Roadster may represent a dream in more ways than one.

The Roadster 2.5, which Tesla is marketing for delivery, is not a new car: It's the fourth iteration of the Tesla Roadster launched in 2008. The differences between the 2.5 and the 2.0 are largely cosmetic and convenience-related. But the idea that a car can run entirely on electricity yet run with the best gas-powered cars is still new to many people.

"We really strive to make the best car, period. Whether that's an electric car or an internal combustion car, we want to be the best," said Dustin Krause, regional sales manager based in Tesla's Chicago store.

In terms of performance, the Tesla folks have a strong argument. Make no mistake: This is a true sports car that runs on electricity, not an electric car that has a sporty bent, and it was engineered from the beginning to maximize the benefits of an electric powertrain.

Using electricity, for example, solves the question of how best to deliver power to the wheels. The electric motor, with its single spinning rotor, doesn't need a multigear transmission to handle its output. Instead, it mates to the rear wheels via a fixed-gear differential. The result is that all the torque of the motor is available immediately.

In other words, you put your foot on the pedal and the car rockets up to speed before you can get it to the floor, with no kickdowns, turbo lags or other impediments to the thrill of acceleration. To quote the freakishly low zero-to-60 time of 3.7 seconds doesn't quite do it justice; this car is flat-out fast. Between about 70 mph and the top speed of 125, the acceleration falls off just a tad as the torque drops, but it's still ample, even for a true sports car.

But just as other drivers might watch longingly for the few seconds before a Tesla peels into the distance, some think a future of plug-in cars may be equally elusive.

"No matter how you do it, at some point you're going to be constrained by how much energy you can store on board," said Brett Smith, of the Center for Automotive Research, an independent research group that advises on public policy.

Smith, co-director of CAR's manufacturing, engineering and technology group, claims the overall cost of delivering power in an electric drivetrain, while dropping, is still about four times higher than it needs to be to compete with internal combustion engines on the cost-effectiveness scale.

Tesla claims that a full recharge, which gives the car a range of about 240 miles, will add less to your electric bill than you would pay to run a car the same distance on gas. It also maintains that other maintenance costs are much lower because the electric powertrain is relatively simple compared with an internal combustion engine.

Still, Smith says the same might not be true throughout the automotive landscape. Electrics in a more affordable range than the Tesla, such as the soon-to-arrive Nissan Leaf, get 100 miles or less to a charge. He also noted the encumbrance of having to spend hours to fully recharge an electric car, as opposed to minutes spent filling up at a gas pump.

"Yes, the Tesla is a unique beast. And it's a wonderful application of the technology," Smith said. "It is not the realistic standard of where the industry is going in the next 10-15 years."

For that matter, plugging in means you're getting power from wherever your house gets it, so a zero-emissions car such as the Roadster isn't necessarily a zero-pollution vehicle. But removing petroleum from the equation reduces your carbon footprint by a significant amount; in a car this fun we'll leave the question of how much for another day.

Although there were no powertrain changes for the 2.5, Tesla added to the fun with more supportive seats (which is a significant change given the cozy interior dimensions typical of a high-end sports car) and a large, easy-to-read GPS display. There's also a new front fascia, hinting at a family resemblance with the Model S sedan due out in 2012, and stylish seven-spoke wheels that help make the low-slung aerodynamic machine even prettier than before. Where the Roadster once made people take notice, now it makes them stop and stare.

Handling on the Roadster is reasonably responsive to driver input, but due to the lack of power steering, that input can be challenging to deliver, especially at lower speeds. The weight distribution of 35/65, tilted heavily toward the back because of the battery pack, isn't ideal for handling, but virtually all of the weight is between the wheels, which helps tremendously. Rear visibility is horrible, typical in the low-slung sports-car class.

Incidentally, in the not-too-distant future you won't have to put up with no practical cargo space and a cramped sports-car cockpit to get an all-electric Tesla. The company plans to launch that Model S sedan in about 18 months, so you can carry your family and your groceries around without burning gas to do it. It will be priced to compete with the BMW 5 Series, which seemed downright practical after exiting a Roadster 2.5 that had been optioned out to the tune of $159,000. (The Roadster starts at $109,000.)

Tesla is playing to market niches that might have low ceilings today. But Tesla is pushing the boundaries of what's possible.

Tesla owners "are very forward-thinking individuals," Krause said. "They really believe that by driving an electric car, they are making it possible for others to do it."

transportation@tribune.com