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2012 Tesla Model S: Is Aluminum Its Secret Weapon?

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Colin Chapman is remembered for many things in the automotive world, but if there's one thing auto journalists have to thank him for, it's an endless stream of column inches dedicated to the weight of cars.

All the calls for lighter vehicles aren't based solely on theory, but a back-catalog of light-weight sports cars that did a great deal with very little.

It's no different these days, only weight is now the enemy of fuel efficiency. Or battery efficiency, if you're Tesla.

The 2012 Tesla Model S may seem portly at up to 4,600 pounds with the largest 85 kWh battery pack, but were it not made of aluminum, the luxury electric sedan would probably weigh a great deal more.

And--thanks to Mr. Chapman--we're well aware that extra weight is detrimental to ride quality, handling, braking, acceleration... and in the case of electric cars, range.

We may not have the best idea of how the Model S drives just yet, but the feedback is certainly positive so far. And with up to 300 miles of range, with the largest battery pack, even the electric car's traditional sticking point has been side-stepped by the Model S. Would it offer that class-leading figure with a heavier, steel body? Unlikely.

Even the Model S base price, at under $50,000, is competitive with gasoline rivals like the Audi A7 Sportback and the BMW 5-Series Gran Turismo. Once, aluminum cars were significantly more expensive than their steel-bodied counterparts.

Of course, aluminum isn't solely responsible for the impressive specification of the Model S--but it could be its secret weapon.

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Comments (11)
  1. seems like once they get a handle on the market they should look to change a lot of components to Titanium and make the structure either friction stir welded or composites.
     
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  2. The price of titanium is about $40 per pound as compared to the price of aluminum at around $1.15 per pound. It will be a VERY long time before we see titanium used as an alternative to aluminum. Most likely carbon fiber will be used (and is currently used) long before any use of titanium.
     
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  3. Another advantage of using an aluminum body shell is that in combination with simple, long lasting and easy serviceable power train the car will basically last for ever.

    30 years after they were build over 60% of the stainless steel DeLoreans are still running. Model S should be able to top that. I reckon the only scenario in which a Model S will a scrapped in the next few decades is after being totalled in an accident.

    This could be the only car on the market in which planned obsolescence wasn't part of the design parameters.
     
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  4. And if you go with the biggest battery, you get an unlimited warranty on it. If my Camry can run for 15-20 years no problem, what's a Tesla gonna clock?
     
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  5. Especially if you live in the northern states where road salt is used to remove ice the roads. Steel car bodies typically only go about 7 years before rust formation starts to occur. Washing the car can help since it can remove the salt residue that acts as a catalyst for rusting. Aluminum especially when protected by a good paint job is extremely resistant to corrosion and the Tesla model S body other then door dings from parking lots could last several decades longer than a traditional steel car body
     
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  6. What's this? A positive Tesla article from GCR? Madness! :)
     
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  7. The downside of AL is its repairabilty after a crash. You can't "bend it back". Wielding it would require different equipments than the body shop is used to...
     
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  8. As a rough guide, compared with a steel body, aluminum saves around 300-500 pounds but is around $1,300-$1,500 more costly. Reducing weight will increase economy in any vehicle, but is much more important when you are carrying around heavy batteries, particularly when you are shooting for long range like Tesla. It's a premium vehicle so the buyers presumably are willing to pay.

    There is really no magic in an aluminum body. Every manufacturer stamps aluminum panels for some body pieces. Assembly of an aluminum body is a bit different, and can use welding, rivets, or bonding. Repairs have to be done by a certified shop and require special procedures.
     
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  9. The most important thing is the efficiency of the drivetrain, but EV's have that in spades! Because an EV is 2-3X more efficient than an ICE, weight matters less on the EV.

    I think that while weight is important, it is aerodynamic drag that is more important. Aero drag is a huge percentage of the load much of the time; especially at highway speeds, but even as slow as 35-40mph, it is about HALF of the load of moving the car.

    The Model S has the lowest coefficient of drag of any new vehicle. The CdA is likely to track closely with Wh/mile.

    Neil
     
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  10. Oddly enough, the more aerodynamic a car becomes, the more important weight becomes.
     
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  11. Aluminum has been looked at by all the automakers for many decades. As recently as the 1990s the cost of aluminum was not competitive for the major body-in-white component (5 times more expensive). Now the cost disadvantage has shrunk to 35%. All of the all-aluminum cars currently produced are in the high rent district. Steel is fighting back with lightweight steel produced by Japanese steelmakers. My personal experiences with aluminum is that I much prefer flexible plastic body panels (as on my Fiero). Those panels never dinged and repair was a snap, unlike the dented aluminum hood on my MGB. It would also be interesting to
    know how many tens of millions have been spent retapping stripped
    aluminum threads, replaced by steel inserts
     
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