Sunday, October 26, 2008

Disappointing Tesla Roadster

I was invited to California this week to test drive a Tesla electric roadster on a closed course. A short course was marked out with cones at a small general aviation airport, and drivers got to try the car out one at a time, each driver getting five runs.

Early cars had two forward speeds, perhaps to reduce noise at speed, but they had clutch problems so now there is just one forward gear. (Electric motors give maximum torque from 0 rpm, so neither a clutch nor multiple gears are necessary.) With no gear box, there was nothing to do but hang on and steer. And of course accelerate and brake.

Acceleration was impressive, all the more so because it required no skill and was accompanied by almost no noise. The brakes were strong but the ABS seemed to allow enough slippage to induce violent squeals from the tires and for me to wonder whether it was actually functioning. While on the subject of brakes, Tesla claim that the car has regenerative braking but it really doesn’t, at least not as normally understood. When you lift off, there is some engine braking effect, as the motor functions as a generator, but there is no attempt to capture energy from actual braking. I did not consciously test how great the engine breaking effect was, but it did not seem any more than a normal car to me, suggesting that one would probably have to be very gentle on the brakes to get the advertised range of 240 miles out of the batteries. Which is not the way one normally drives a sports car.

Unlike the ABS, the traction control is very obtrusive, and unfortunately the track layout made this shortcoming very obvious. It incorporated a long 180-degree bend during which the car would understeer violently. At least, the Tesla engineer blamed this behavior on the traction control, which in theory can be switched off though we were not allowed to do so for this test. I suspect there might be more to it than that. In any case, it defeats the object of traction control if you have to switch it off to make the car safe.

These shortcomings may be less obvious in daily use, though this is not the sort of car in which one is likely to be doing a lot of motorway cruising. The car has more or less zero luggage space, so can be regarded only as a toy or maybe a commuter car. Given its price ($109,000) and heritage (it is built by Lotus on a stretched Elise chassis) one would hope that it would be fun to drive, but from my short test I think a Honda Fit might be more enjoyable. Everyone I met from Tesla was friendly and appeared knowledgeable, and I wish them well, but somehow I feel that the company at its core doesn’t quite get it. Not that there is anything about the car which could not be fixed, especially if they could involve Lotus in developing out the flaws.

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