Tesla Roadster

Debut: 2007
Maker: Tesla
Predecessor: no


American wants to revolutionize the automotive world with this electric car...

Two silicon valley IT engineers founded Tesla Motors in 2003. As outsiders, they dreamed of revolutionize the automotive world by introducing an electric sports car. They believe there will be sufficient demand from Californian environmentalists, Hollywood stars and silicon valley IT executives to sustain multi-thousand units sales per year. Their idea attracted billionaires like Elon Musk (founder of PayPal), Lorry Page and Sergey Brin (both are founders of Google) to invest some US$60 million into Tesla. Five years later, the first production Tesla Roadster finally reached the hands of customer.

Like many other American dreams, the management of Tesla found the road to success more bumpy than originally thought. This is because they lack experience in automotive field. They know their weaknesses as well, so in the beginning they decided to outsource production and engineering as far as possible. As you might have predicted from its looks, its chassis was designed by Lotus based on Elise. Many components are shared with Elise as well, such as the spaceframes made of extruded aluminum, the aluminum double-wishbones suspensions (though with bespoke springs and dampers), the windshield and interior parts. However, the body panels are made of carbon-fiber instead of glass-fiber to save weight. Production of the car takes place at Lotus’s factory in Hethel, England, alongside Elise.



The road to success is more bumpy than originally thought...

The chassis has its wheelbase stretched for 52mm to accommodate a big lithium-ion battery pack in front of the electric motor. Unlike big car makers, Tesla could not ask giant battery makers like Sanyo, Matsushita or LG to develop a battery pack specially for its automotive application. Therefore its battery pack is made of 6831 pieces of laptop computer-grade lithium-ion battery cells, plus temperature sensors and cooling system. The IT guys claimed that it offers excellent performance, e.g. 220 miles range and 3.5 hours charging time, but it is bulky and heavy at 450 kilograms. This lifts the kerb weight to 1220 kg and worsens the weight distribution to 35:65 front-to-rear.

The 3-phase AC inductor motor is made in Taiwan. It produces 248 horsepower and 205 lb-ft of torque. The torque curve, however, is very different from conventional engines, as it develops peak torque from 0 to 6200 rpm, then decline linearly. Such strong torque means Tesla only needs a 2-speed manual gearbox to achieve 0-60 mph in 3.9 seconds and a top speed of 125 mph… at least according to plan.



Elise-based chassis offers excellent ride and handling...

Unfortunately, Tesla’s inexperience was revealed in the engineering of gearbox. They selected a gearbox design that was not strong enough, nor could they manage the violent gearshifts through control software. This caused a year of delay to production. Embarrassingly, Tesla decided to equip the early production cars with the first gear removed, so using the second gear only 0-60 mph was increased to 5.7 seconds. Later on, it announced it will use a new single-speed gearbox to solve the durability and shifting problems, while a torquer motor will compensate and restore the original 0-60 mph claims. However, at the time of writing this so-called Powertrain 1.5 is still on testing stage.

On the Road

In stationary, the Tesla Roadster looks every bit like a slightly longer and more civilized version of Lotus Elise. It attempts to be more “luxurious” than the Lotus, but like the last effort by Opel Speedster, its cockpit is still more like race car than grand tourer. To enter the cockpit, you have to step across a wide sill and drop into a thin bucket seat. The tub is narrow. The seat is mounted right on the floor. The plastics are nasty. The insulation of the cockpit is poor. Though there are ABS, traction control, cruise control, power windows, air-con and i-Pod connectivity as standard, the whole cabin looks and works like Lotus Elise. Well, the 3-spoke steering wheel is donated by Opel Speedster.

  

Like Opel Speedser, its cockpit is still more like race car than grand tourer...

The similarity ends once you start the motor and engage the forward gear. A violent acceleration force pushes your back right from the gear engagement, which is quite a discomfort. The force keeps pushing constantly while the motor spinning smoothly like a washing machine. The mismatch between acceleration and noise is odd. The lack of gearshift amplifies this strange experience. Yes, the Tesla is very fast to get off from traffic lights and up to about 100 mph, but is it as engaging to drive as conventional sports cars ? Is it as thrilling at high speed ? The answers are negative.

Fortunately, it rides and handles as well as conventional sports cars. It runs very much like a heavier and slightly more civilized Lotus Elise. Thanks to the longer wheelbase and softer suspension setting, it rides with suppleness unmatched by many sports cars. Its unassisted steering provides good communication and precision. Its handling is a little more rear-biased than Elise due to the weight of battery, but it still provides excellent grip, poise and agility. Larger brakes handle the extra weight effectively.

Unconventional cars ask for unconventional prices. Tesla Roadster is no exception. While a top supercharged Elise costs $55,000 in the US, the Tesla sets you back at $100,000. In the UK, their price gap is even wider - £36,000 vs £80,000. Only people with strong environmental conscious mind and deep wallets simultaneously may consider purchasing it.
The above report was last updated on 14 Jul 2008. All Rights Reserved.
 





Specifications




General remarks

Roadster v1.0
Roadster v1.5

Layout
Mid-engined, RWD
Mid-engined, RWD
Chassis
Aluminum tub
Aluminum tub
Body
Glass-fiber
Glass-fiber
Length / width / height 3946 / 1752 / 1127 mm 3946 / 1752 / 1127 mm
Wheelbase 2352 mm 2352 mm
Engine
3-phase AC induction motor
3-phase AC induction motor
Capacity
-
-
Valve gears
-
-
Induction
-
-

Other engine features
-
-

Max power
248 hp / 8200 rpm 248 hp / 4500-8500 rpm
Max torque
205 lbft / 0-6200 rpm 276 lbft / 0-4500 rpm
Transmission
2-speed manual
1-speed

Suspension layout
All double-wishbones
All double-wishbones
Suspension features
-
-
Tyres front/rear
F: 175/55WR16
R: 225/45WR17
F: 175/55WR16
R: 225/45WR17

Kerb weight
1220 kg
1247 kg

Top speed
125 mph (c)
125 mph (c) / 121 mph*

0-60 mph (sec)
3.9 (c)
4.0* / 5.0**

0-100 mph (sec)
-
11.1* / 14.3**

Performance tested by: *R&T, **Autocar






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