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Thursday, May 7, 2009

Closer look: the Tesla Model S



There is much excitement and publicity surrounding the launch of the long awaited all electric sedan from Tesla Motors and more details have emerged since the Tesla Model S was unveiled. The specs that have officially been announced are not yet substantial enough for a full technical review at this stage, but we do know that the EV sedan has a top speed of 130 mph, is capable of 0-60 in 5.6 seconds, charges in 45 minutes and has a 160 mile (256 km) range with the standard battery option. According to the company's website we can expect to see an AWD option somewhere in the future and although it's not not officially stated, according to reporters at the the unveiling who were able to question Tesla engineers the Model S will be rear wheel drive (RWD) in its standard configuration.

The five door sedan is designed to seat 5 adults and two children (though we're not clear on exactly how) Tesla says they will offer upgrade battery options for 230 miles (370 km) or 300 miles (480 km) on the standard 160 mile (256 km) range. No pricing or further details have yet been provided on these options. They claim the battery is 'swappable' in 5 minutes but we are left wondering if this means a 300 mile battery can be swapped into a car purchased with a 160 mile battery much like the Heuliez WILL. The company has announced plans to rent or lease high capacity battery packs which offer a 300-mile range but it's not clear if these can be rented for a weekend trip and returned when you go back to your week day commute.

While the 160 mile 'Standard' Model S comes with a 42 kw/hr battery pack the larger 300 mile battery pack is 70kw/hr and weighs 1200lb (544 kg). It is made up of 8000 cells compared to the 6800 in the Roadster. With the larger battery included the Model S weighs in at 3825 lb (1734 kg). The lithium-ion batteries are mounted under the floorpan for an ultra-low center of gravity and the majority of its chassis and body panels are made of lightweight aluminum to keep the vehicle's overall weight reasonable. There will be a significant weight difference across the range of battery sizes which may pose a challenge to the Tesla chassis engineers if the various sized packs can be “hot swapped” as installing the larger 300 mile battery will be like putting a load into a truck - it's almost double the weight of the smallest pack.

The Model S carries an on board battery charger that will work with 120, 240 and 480 Volt outlets. Using 480v the charger offers 'QuickCharge' which can fully charge the battery in 45 mins (we presume that means the smaller 45kw/hr pack).

Reportedly (but again not confirmed by the website information), the Model S will be powered by a water cooled 300 hp (220 kw) electric motor with 400ft/lb (541 Nm) from zero rpm. We do know the Tesla Model S comes with the same type of single speed transmission found in the Roadster but the only official word on the motor is that it will be a “proven powertrain from a leading EV manufacturer”.

The prospect of an All wheel drive (AWD) version will be something to look forward to if Tesla use the same 300 hp motor front and rear giving a total of potentially 600 hp. While adding AWD capability to an EV is much simplified compared to a combustion engine vehicle it also adds weight to the vehicle with the second motor and transmission. Perhaps the AWD version is the the one referred to as the future 'performance' version of the Model S capable of sub 5 sec 0-60 times.

Inside, there are no dash board controls to speak of. Every button has been replaced by a 17″ 3G capable touchscreen computer.

The Drag coefficient of “around” 0.26 is equal to the current Toyota Prius and a significant improvement over the Roadster at 0.35.

For USD$57,400 ($49,900 if you factor in a federal tax credit of $7,500) Tesla aims to offer the car for sale in late 2011. The company has taken over 500 reservations in the first week and plans to produce around 20,000 units per year. Unlike Fisker who have sub contracted vehicle production to the same company that builds the Porsche Boxster, or the recently announced Detroit Electric partnership with Proton, Tesla want to go it alone. Despite the recent downturn in global auto sales leading to an enormous amounts of idled automotive manufacturing capacity, Tesla have decided to take the hard road and start from scratch with the construction of a green field automotive manufacturing site, pending government funding and the selection of a site. Tesla were in fact scheduled to begin construction of the Model S factory on the first site chosen for Model S production in Albuquerque New Mexico back in April 2007, but that never commenced. Lets hope the late 2011 delivery date for the Model S is not delayed to the same extent.

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