Third-Generation Tesla Won’t Be Made of Aluminum, Says Tesla VP of Engineering

Third-Generation Tesla Won’t Be Made of Aluminum, Says Tesla VP of Engineering

Tesla’s next-generation, affordable electric car — the one formerly known as the ‘Model E’ — won’t inherent the all-aluminum construction of its bigger brother, the Tesla Model S.
That’s according to Chris Porritt, Tesla’s Vice President of Engineering, who says that Tesla’s third-generation plug-in will be manufactured using “appropriate materials” for its price point and market segment.
Porritt, who left British prestige marque Aston Martin last year to take up a place at the Silicon Valley automaker,told AutoCar that cost concerns were paramount in finalising the design of Tesla’s first truly affordable electric car.
Talking of the Model S design and construction method, which makes extensive use of aluminum, Porritt said very little of existing Model S manufacturing processes will be used in the as-yet unnamed third-generation Tesla.
“I expect there will be very little carry-over. We’ve got to be cost-effective,” he said. We can’t use aluminium for all the [third-generation Tesla's] components.”


I hope rust prevention will be addressed by other means...This car has to be made to last long, unlike current competition

SamO | 01/07/2014

Elon said long ago that gen III would not be aluminum. Too expensive. But very sad.

DTsea | 01/07/2014

Why sad?

SamO | 01/07/2014

Aluminum doesn't rust.

DTsea | 01/07/2014

Aluminum corrodes just fine. Google 'exfoliation corrosion of aluminum alloys.'

SamO | 01/07/2014

From the first link:

How to prevent exfoliation corrosion? Exfoliation corrosion can be prevented through:
the use of coatings
selecting a more exfoliation resistant aluminium alloy
using heat treatment to control precipitate distribution.

Bimetallic corrosion is more likely than exfoliation. Especially if your car isn't driven in a tropical marine environment.

That being said, aluminum is FAR LESS LIKELY to corrode than steel. Not impossible. But rare, by comparison.

DTsea | 01/07/2014

Depends on the environmnent. Yes, better than alloy steel- not nearly as good as corrosion resistant (aka 'stainless') steel.

Aluminum is at an extreme of the electrogalvanic scale so is vulnerable to galvanic corrosion, as well as pitting.

SamO | 01/07/2014

Cars are rarely made of stainless steel. So we are comparing mild steel and aluminum.

Mild steel suffers from corrosion in the best of conditions. When exposed to salt, dirt and water, rusts relentlessly.

Rust is it's natural state.

Not so with aluminum.

Iowa92x | 01/07/2014

I was correct.

Iowa92x | 01/07/2014

Uh, modern cars don't rust. Mine is 10 years old, dinged up, and probably won't rust for another decade. This is not 1954, auto companies apply coatings to retard the rate of oxidation on steel. Steel will be just fine on Gen 3, most people want to pay as little as possible.

centralvalley | 01/07/2014

SamO--your photograph looks like Bodie! Wonderful place!

SamO | 01/07/2014

Modern cars DO rust . . . if you are going to assert something so contrary to common sense, at least be able to provide a citation.


Don't Be Fooled Modern Cars Rust Too.

From the article:

"Rust problems still crop up regularly during the testing procedure for cars - under German law vehicles are subject to a stringent safety test every two years. Among the cars aged between three and five years old examined by the GTÜ, 3.6 per cent were found to have chassis, frame or bodywork defects, of which 2.5 per cent were caused by rust.

Among older cars up to seven years old, the overall figure was 4.1 per cent - 3.1 per cent of them succumbing to rust.

For cars aged over nine years, the figures were 13.6 per cent and 11.6 per cent respectively."

SamO | 01/07/2014


Wish I'd taken that photo. Very cool. But just an internet screen grab :-)

bigd | 01/07/2014

1st car daddy bought SamO

Last car SamOs daddy bought him

NumberOne | 01/07/2014

Modern cars can still rust. Make no mistake about that. Most cars have a coating on the undercarriage to help prevent rust, but if you have a bad ding, where paint is chipped to bare metal it needs to be addressed or else a rusty hole will eventually replace it. It does take longer for cars to rust, even with bad damage, but aluminum takes even longer to start corroding.

Dramsey | 01/07/2014

Modern steel car bodies use a variety of techniques and coatings for rust prevention. While even "stainless" steel can rust, modern car bodies are much more resistant to corrosion than they were in the past. I suspect that anyone who takes decent car of their cars could easily expect a decade of rust-free ownership with a modern steel bodied car, excepting perhaps those that live in states that salt their roads in the winter.

Full aluminum car bodies are relatively recent. Although aluminum had been used for individual body panels for decades (the Porsche 928 is one example), I think the Audi A8 was the first car with a fully aluminum body.

Aluminum is lighter and more corrosion-resistant than steel, but is much more expensive to both produce and repair.

(It will be interesting to see how Ford's new aluminum F150 will work in the real world...)

richcockrell | 01/07/2014

So given that steel cars do corrode, what do you think the folks at Tesla will do to mitigate that concern.

DTsea | 01/07/2014

The usual. Coatings etc. Depends on salt application.... no salt no rust. But, oops, salt makes aluminum corrode too.

To make an affordable car it will NOT be the same as a model s. Can't be. But add 'aluminum' to why model s is better than MB, Audi, etc threads if you like.....

Iowa92x | 01/07/2014

Folks, modern cars don't often rust, even after a decade. I live smack in the heavy salt, 20 below zero in the winter. My steel car is a decade old, 130,000 miles and no rust. Yes, if you bang your car in an accident and raw steel is salted, it will eventually rust.

But barring that, nope. Does anyone here not drive an older ride?

Timo | 02/07/2014

When I was young I drove a 10 year old car for about five years. So car age was about 15 when I sold it. Small rust dots, but nothing major. This was now nearly half a century old car. You just have to take care of your car.

Red Sage ca us | 02/07/2014

Dramsey: The Honda/Acura NSX says, "Hello."

"The NS-X was the first production car to feature an all-aluminium monocoque body, incorporating a revolutionary extruded aluminium alloy frame, and suspension. The use of aluminium in the body alone saved nearly 200 kg in weight over the steel equivalent while the aluminium suspension saved an additional 20 kg; a suspension compliance pivot helped maintain wheel alignment changes at a near zero value." -- Wikipedia

Red Sage ca us | 02/07/2014

Making the Case for Aluminum...

I'm hoping that Ford's using aluminum on their best selling F-Series vehicles will lower the price of the commodity. That way Tesla Motors will be able to use aluminum, instead of steel, in their Generation III vehicles. That would allow for lighter weight and more driving range, thus better EPA ratings for both Ford and Tesla.

From 'Difference Between Steel and Aluminum':
Steel strength over aluminum is almost the same, but steel is three times heavier than aluminum.
⇒ This is why the use of aluminum is so important in either fuel economy or in gaining range.
Steel has a preserving quality, even after thousands of load cycles, but aluminum will fatigue and destroy.
⇒ So aluminum is usually extruded at roughly 20%-30% thicker than steel to guard against that eventuality.
Aluminum has more malleability over steel, as it has more bending density compared with the density of steel.
⇒ This is what makes aluminum have better crumple zone reaction than steel, allowing for a safer vehicle to operate.
Some are concerned about the expense of doing repairs on a fleet of mass market aluminum cars need not worry. A relatively sudden increase in the number of affordable/attainable vehicles made of aluminum will bring down the price of bodywork. Insurance companies would insist upon it. Those who know better have already stated that aluminum is actually easier to work with than steel. Body shops charge more because of the perception that the material is only used on exotic vehicles, and thus the owners can afford to pay more.

Chris Porritt is much more likely to know which direction Tesla will take on this than I am. But I am certain that ALCOA would be more than happy to work with Tesla on GIII. There are very valid reasons why aluminum is used in construction of both marine and aeronautic vessels. When all points are considered, the only factor in favor of steel is its initial cost. But when a vehicle is engineered with a weight budget as the primary concern, aluminum always permits 'a more robust structure'.

All of this has of course been debated at great length all over the internet for ages, and ages... But by and large, aluminum wins versus steel. I really do hope that Tesla forgoes the use of steel with GIII in favor of aluminum.

Timo | 02/07/2014

There is also a range vs cost issue. A lighter frame allows less batteries to be used for same range, and batteries, even more advanced ones, still cost a lot more than aluminum or steel.

In fact, if the car is small enough and aerodynamic enough even something very expensive like CFRP might end up being cheaper than steel, because it allows you to use less batteries for same range.

OTOH probably something like FRP with aluminum frame would get you best result for weight/strength/safety when you add battery weight in the equation.

Less weight also gives better performance. A 1000lbs car requires half the torque to accelerate as fast as 2000lbs car.

Timo | 02/07/2014

Or should I say large enough and aerodynamic enough. Size and mass correlate more than size and aerodynamics (as long as you go with side by side configuration and not tandem), so with larger car you benefit more from lighter materials.

Red Sage ca us | 02/07/2014

I believe that ALCOA would gladly go 'all in' on this if Tesla Motors asked them to...

curiousguy | 02/07/2014

i dont think corrosion was the reason why model-S is made of aluminum and not some steel alloy. from what i remember reading it had to do with reduced weight. it will be interesting to see how the weight issue will be tackled by the "affordable" model.

mb30 | 02/07/2014

I really don't think this is a big deal. Cars in this price point are significantly less likely to be kept as a collectible etc... and are also more likely to be turned over well before it really rusts. If you take care of your car (like most things in life), you'll be fine. Even with Elon mentioning that it wouldn't be aluminum, i never thought it would be anyway. They are trying to make a really good car, for right around 35k. If they plan to meet the goals that are really important (range, power etc...) they have to save money in other places and this is an obvious place to start.

DTsea | 02/07/2014

Guys... strength to weight ratio for all metals is the SAME. Only LOW GRADE steel is inferior to aluminum.... but they are not going to heat treat weldable aluminum alloys to the highest strengths, either.

Mass market driving down commodity price- not going to happen. Aluminum is already a mass market commodity. It requires large inputs of electricity to make it from bauxite, and all the recyclable aluminum is not going to get cheaper. Maybe the opposite if demand rises for high grade alloys.

Repair- steel is cheaper to repair. This will matter in a cheaper car.

Red Sage ca us | 02/07/2014

I think a lot of the weight reduction will be due to the weight of the battery packs going down. Some have thought incorrectly that 200 miles would be the maximum range of GIII. So they presumed it would have a battery pack with only 80% of the battery cells found in the Tesla Model S 60 for a yield of 48 kWh. They are almost, but not quite correct in that regard.

JB Straubel said that the 85 kWh battery pack in the Tesla Model S, released in 2012, actually used fewer 18650 cells than the 53 kWh battery pack in the Tesla Roadster, from 2008. In the course of four years, the energy efficiency had improved by 40%. What if the same happens by 2016?
Vehicle # Cells
S 85 ~7000
S 60 ~5000
GIII 85 ~4200
GIII 60 ~3000
Combined with a projected 30% lower cost of batteries with the opening of the Gigafactory, that means that as time goes by, Tesla's margins on the GIII will go up. That will allow the cars to be affordable, while allowing Tesla to put more cars on the road per cell count.

In this example, the GIII 60 would use only 60% of the battery cells that were originally in the Model S 60, while the GIII 85 would use only 60% of the battery cells that were originally in the Model S 85. That would make for a weight savings of around 500 pounds with the 85 kWh version and over 350 pounds off the 60 kWh version.

Elon Musk has said that the GIII would compete with the BMW 3-Series and be 20% smaller than Model S. I believe that means he means to get a curb weight of around 3,700 pounds on the new releases. If my WAG calculations are sound, that would mean the battery pack would be as much as 780 pounds of that total. Still on the hefty side, but if you consider a V8 engine might weigh 440-520 pounds, and would still need a transmission, exhaust system, and various accessories as well, it comes to about the same. So the weight penalty would still not be too bad.

But how to get the rest of the car at or below 3,000 pounds? Using the Acura NSX as an example, using aluminum instead of steel you saved 440 pounds or so. You can even use the Model S as an example, because without the ~1,300 pound battery pack, it is 3,400 pounds. 80% of that is 2,720 pounds. Add a 780 pound battery pack and you have a total of 3,500 pounds with aluminum construction. A steel chassis would likely weigh in at 4,070 pounds total.

This is where cost benefit analysis comes in. My vote is for aluminum, because if you can save over 1,000 lbs from the Model S you will get a significant increase in range. If you just want to get bragging rights to achieve 'over 200 miles' of range, steel will be fine enough. You'll get there. But if you really want to do something special that moves people to buy with no concerns for either 'range anxiety' or even 'range awareness', the lighter aluminum based vehicle would get around 350 miles of range with the 85 kWh battery pack.

It's a matter of priorities. Save money up front, have a lower range. Spend money up front, get a higher range. Which is more likely to expand the appeal of the electric car?

Timo | 03/07/2014

200 miles minimum. You actually need to have rather large battery pack if you want to use SC network as long as they are using low power density batteries.

Here is a pretty good summary of what causes Model S to weigh so much: (chrisdl messages starting from about half-way of the thread).

From there you see that frame + panels is actually only about 25% of the car total weight. Cutting 20% of from 25% is not that much. You need to shave mass from all around of the car to get it below 3000 lbs and still have safety of Model S.

vgarbutt | 03/07/2014

I hope the frame, the safest on any car made, will remain the same, or at least as safe. I wager at least 250 usable miles on a full charge. Just want to put that out there ;>)

Brian H | 03/07/2014

RS's summary of trade-off between cost, weight, and range is correct, of course. But his rhetorical question "It's a matter of priorities. Save money up front, have a lower range. Spend money up front, get a higher range. Which is more likely to expand the appeal of the electric car?" has a different answer than the one he rhetorically implies. There's a "knee" in the function, and cost dominates above about $35K/200 mi., for true mass market appeal and defusing the twin cost and range barriers to entry.

The true economics of TCO will move buyers higher than the knee, in reality and over time. But they have to get past that point, first.

Red Sage ca us | 03/07/2014

Yeah. I really hate rhetorical questions. I hit myself with an imaginary hammer every time I find myself using one... I usually try to rephrase, to make the same point without actually asking a leading, rhetorical question. But sometimes I'm really tired, a bit loopy, or just plain lazy, and I roll with it anyway. ;-)

judimasters | 03/07/2014

This is all very scientific but... I am saying Bamboo! Self sustaining, lightweight and renewable. NOW she's on to something!

Red Sage ca us | 03/07/2014

Renewable fibre vehicles would be awesome... If the NHTSA crash tests showed the finished product to be properly survivable... If insurance companies didn't mind totaling the cars out for every collision, no matter how minor... If the Great State of California hadn't made all the wonderful glues, lacquers, and bonding agents illegal for use in manufacturing in the state... Other than that -- great idea! ;-)

Timo | 04/07/2014

Make frame using steel or aluminum, panels using FRP of some kind. Enclose the frame in that and you have corrosion protection. FRP panels don't rust and are lightweight.

Anyway, if you look at what the different parts of the Model S weigh you notice that frame & panels is not that much. You can't save much at weigh only from changing steel to aluminum when everything else weights about 3000 lbs. Even if you make car exterior using bubblewrap it would still weight that 3000 lbs. You would need to change a lot more than that.

Seats, wheel & rims, differential, battery pack shielding etc. etc. You can shave off weight from everything.

Red Sage ca us | 04/07/2014

Timo: FRP Panels - Fiberglass Reinforced Plastic Panels... just might work from an engineering perspective. Lightweight materials, with the color baked through into the surface would make for a consistent finish. Bumper areas front and rear on the Tesla Model S are already made of plastic and look just fine. They should also be rather easy to remove & replace if necessary for either maintenance or repair.

People in the US tend to express displeasure with 'plastic cars' though. They expect 'quality' to be expressed in terms of the weight and heft of steel and iron -- no matter how inefficient it may be. That was a major complaint about General Motors products from Saturn and vehicles such as the Pontiac Aztek. People can't get over the notion that these materials are 'cheap'. Then they cry bloody murder when they get a repair bill for bodywork on a Chevrolet Corvette.

That said, most people have finally gotten away from the perception a vehicle was 'unfinished' if it didn't have big, hulking, chromed bumpers. Albeit, it took most of the past thirty years to wean them off that perception. And pickup truck owners are still in the process of acceptance. Manufacturers of all types of vehicles still provide a 'chromed grille' look -- even when the whole thing is plastic though.

One thing to consider is that Tesla Motors might be able to make these in-house, rather than using an external supplier. It has been mentioned that one of their goals is to increase the domestic content of their cars. The aluminum they use is from ALCOA in Tennessee. It might be counterproductive if they had to get such panels from a foreign source. But their overall costs might go down if they could fabricate their own. On the other hand, that still leaves a lot of stamping equipment with nothing to do but make parts for Model S and Model X...

Molded Fiber Glass Companies - Automotive and Recreational Vehicles

Zhenjiang Yangyi Automotive Parts

carlgo | 04/07/2014

SamO: Yay, the Bodie car! I love that car. I love Bodie.

Read up on the electrification of Bodie. Out in the the middle of nowhere there was this vast electrically driven enterprise. Check out the huge abandoned electrical motors, the big switches and other industrial sized components. Most of us don't get to see big electrical devices.

It was all based on Tesla's engineering. I forget the tech details, but evidently the electrical system up there was derived from radical Tesla engineering, was in some way different from normal electrical systems found in cities and other industries. It was more advanced. The electrical people here can perhaps explain it.

L. Stanford was a big investor and Stanford was pretty much founded with Bodie gold. Of course a lot of Tesla people have a Stanford background.

So, all Tesla owners should plan a pilgrimage up to Bodie some time. Without Bodie, there may not have been a Tesla.

BTW, rust is not a problem with modern cars. In CA anyway. Our shop almost never did a rust job in recent years. Back when I first started we patched up endless rusted cars, but the problem gradually went away to virtually zero. Rust-proofing technology is very good.

Bubba2000 | 04/07/2014

What is the difference in the price of Steel versus Al for the MS? I am not an expert in this area, but my estimate of the diff was $1,500-2.000. Of course, there are additional cost to welding, reinforcing Al. The weight savings resulting in less battery capacity should make up for Al use? BMW went to the cost of using Carbon Fiber.

Yes, MS is a little over reinforced, but is like the safety it provides. It is stable at hi speeds, no rattles, squeaks. I got the acceleration, or the brakes to get out of most situations, I would like safety features like smart cruise, collision avoidance, lane change warning and tracking, bird eye view of surrounding traffic.

For Version 1.0 it is a well designed and engineered car. Elon took no chances. Look at GM. F Pinto anybody?

Red Sage ca us | 05/07/2014

Bubba2000: Yeah, that's something else that people may miss if the next Tesla is made of steel... the absence of rattles and squeaks. Trust that if early prototypes of steel cars have such foibles, Elon Musk will veto steel and other 'appropriate materials' to make the car right. With electric cars not having an ICE to disguise or mute chassis vibration and settling sounds behind the constant drone of an engine and exhaust notes, anything that can be heard at all becomes a nuisance and an eventual cause for concern, whether there is anything wrong with the vehicle or not.

db | 25/11/2014

Don't you think the next generation may use composite and carbon fiber?

Darko | 25/11/2014

I would like to think carbon fiber will be used, that would continue "made to last" feature that was introduced with Model S and which made Tesla different from all other volume-produced cars.

ian | 25/11/2014

If the costs of producing the parts that are carbon fiber are in line with the goal of selling the car at the previously stated goal of $35,000, we'll likely see it used. If not, then likely not.


Darko | 25/11/2014

The cost of carbon fiber parts could be brought down. Similar to the Gigafactory. If the plan is to produce 100,000+ bodies per year, I expect significant cost reduction could be realized.

3s-a-charm | 26/11/2014

With the news that BMW and Tesla are in talks... I expect we may see Carbon Fiber (CFRP) in future Teslas.

vgarbutt | 26/11/2014

Hmm maybe Tesla will trade battery packs for carbon fiber bodies! ( or some other arrangement that comes out even.)

blue adept | 26/11/2014

I wouldn't be so inclined to entrust the structural integrity of the vehicle chassis/body, and the life/lives of the occupant(s), to a third party vendor, particularly one that has publicly shown such a degree of contempt for adoption of the technology.

The cautiously aware beware!

Anemometer | 26/11/2014

Its highly possible.. if you compare the price of a 1 series vs an i3, you are getting a similar sized car for not that much more money when you condiser the i3 is carbon and aluminium. (Well in the UK at least). I think the original statement not aluminium was very vague. Given Elon's comments that the CF seems relatively good value, might be a nod to investigating that direction. Could still be a steel skateboard/trolley underneath though. Maybe.

Brian H | 27/11/2014

Solid titanium.

FREE ENERGY | 27/11/2014

The very first AUDI A2, from 1999, was a car built by aluminum, inside out, but still standing out as a new car, from a short distance...if you get my point.