A Very Light Electric Car is Much Better than the Model S or Model E Oliver Kuttner

[breathe]

I'm a big fan of Tesla Motors and I pick up my Model S - P85+ on May 28, 2014. I expect to be very happy with it, and I plan to do as much as I possibly can to help Tesla sell more.

However to achieve Tesla's stated goal of making a mass market electric car at prices that everyone can afford, the approach of the Model S. and everything I have heard about the Model E is not the best approach. The Model S is simply too heavy to ever be a cheap as the mass market needs it to be. It's a big heavy car and it will always have a certain cost per pound.

Now I don't know exactly what is planned for the Model E, but I do know that it will be extremely difficult to simply build a scaled down Model S, at a price that everyone can afford. This will be true even if volume goes up a lot.

Here's a video by Oliver Kuttner. He's the leader of the team that won the 5 Million Dollar X Prize for a car that got over 100 MPG. I belive Kuttner's approach to be much better than anything I have heard about the Model E. Kuttner's car can be made very safe using techniques derived from race cars, and it can be much cheaper than anything currently on the road. By the way Kuttner is a big fan of electric cars even though his X Prize Winning Edison 2 was gasoline powered.

It's 30 minutes long and very good.

 

[qwk]

It's very easy to talk about building ideal things, but building them is another story. The fact is that batteries are heavy, and other than waiting for energy density to improve(which takes time), there is little else that can be done. One has to remember that there are many regulations for automobile manufacturers that one off, or small scale builders don't have to follow.

 

[Todd Burch]

1. Model E will not simply be a scaled down Model S. To suggest that is silly.

2. To indicate that weight and cost are proportional is also silly. In fact, most of the time it's the opposite. The lighter you get, the more it costs.

3. Everything that has a price and mass has a cost per pound. So? The former is not necessarily indicative of the latter.

4. Of course a light electric car is better than a heavier electric car--of equivalent specs. A light gas car is better than a heavy gas car--of equivalent specs. So?

Almost everything in engineering is based on tradeoffs. You can make something very light and get great efficiency, but typically at the expense of cargo capacity, crash safety, range, performance, or something else.

The best engineers are able to find the right balance and maximize one benefit while minimizing its corresponding drawback.

 

[abasile]

I have a family and would prefer a vehicle with more passenger space than the Model S. So for me, the Model X is better. On the other hand, if I'm going somewhere solo, then my road bicycle is often my preferred mode of transportation.

 

[MikeC]

By the way Kuttner is a big fan of electric cars even though his X Prize Winning Edison 2 was gasoline powered.

Not surprising from someone who named their car Edison.

 

[Jaff]

Probably more polite than calling it the "Douchebag II" though...:wink:

Not surprising from someone who named their car Edison.

 

[RobStark]

If Mr Kuttner can build a better mass market car than a Tesla 3rd Gen Sedan let him build it.

BTW Tesla has abandoned the Model E trademark.

 

[Doug_G]

Talk is cheap. Building a practical DOT-approved mass production vehicle is not.

 

[ThosEM]

The funny thing about weight of an electric car is that it doesn't seem to make much difference to the energy efficiency, despite the intuition we have picked up from owning ICE cars. All that energy going into accelerating the mass comes right back with regenerative braking; hence a heavy battery is no big show stopper, and a large, heavy car like the Model S gets almost the same energy efficiency as the much smaller Leaf. Hybrids also benefit from this up through larger car sizes, for example our Lexus RX400h picked up nearly 10 mpg over the ICE version.

Of course, Tesla has bent over backwards to lighten (and streamline; a different issue) everything about the Model S as much as possible to reduce the overall impact of a very heavy battery, but the bottom line is that it is not necessary to lighten a car to race car standards to get 100 MPGe, IFF one is running an electric car with excellent regenerative capture of invested energy.

 

[Todd Burch]

The funny thing about weight of an electric car is that it doesn't seem to make much difference to the energy efficiency, despite the intuition we have picked up from owning ICE cars. All that energy going into accelerating the mass comes right back with regenerative braking

Exactly. With an EV, the worst part about weight is performance/handling--not efficiency. As you mention, with more mass, you have more energy to recapture using regen. It's certainly not as good as having a lighter car, but assuming you're using regen, extra weight carries nowhere near the penalty you have with an ICE, where all that extra kinetic energy is just wasted as heat.

 

[Doug_G]

Areodynamics is far more important than weight. The main reason why Model S consumes more power than a Leaf is that it is larger and displaces more air. The Roadster is more efficient than the Leaf for the same reason.

 

[ItsNotAboutTheMoney]

The funny thing about weight of an electric car is that it doesn't seem to make much difference to the energy efficiency, despite the intuition we have picked up from owning ICE cars. All that energy going into accelerating the mass comes right back with regenerative braking; hence a heavy battery is no big show stopper, and a large, heavy car like the Model S gets almost the same energy efficiency as the much smaller Leaf. Hybrids also benefit from this up through larger car sizes, for example our Lexus RX400h picked up nearly 10 mpg over the ICE version.

Of course, Tesla has bent over backwards to lighten (and streamline; a different issue) everything about the Model S as much as possible to reduce the overall impact of a very heavy battery, but the bottom line is that it is not necessary to lighten a car to race car standards to get 100 MPGe, IFF one is running an electric car with excellent regenerative capture of invested energy.

Well, regen definitely helps, but weight also affects rolling resistance and energy spent overcoming rolling resistance is lost. However:
- Electric motors have broad efficiency
There's no narrow performance band problem
- Batteries have low energy density
- Performance depends on battery capacity
Appealing cars have to add a lot of battery weight
- Humans are heavy
Dependency on light weight causes efficiency degradation as you fill the car.
- Long trips are done at highway speed
At higher speeds, aerodynamics become more important than rolling resistance. So, reducing vehicle weight does allow for a reduction in battery capacity but if highway range is important and with the additional weight of people and aerodynamic drag the allowable capacity reduction from other weight reduction might only be 1/3:1 and the efficiency gain overall would similarly be only a fraction of the weight reduction.

 

[TurboFroggy]

2. To indicate that weight and cost are proportional is also silly. In fact, most of the time it's the opposite. The lighter you get, the more it costs.

3. Everything that has a price and mass has a cost per pound. So? The former is not necessarily indicative of the latter.

Case in point: Chrysler/Dodge used to be asphalt in the doors of minivans for sound dampening material. Seems ridiculous now, but Chrysler/Dodge didn't care about MPG and asphalt was cheap. Oh and Chrysler/Dodge still doesn't care about MPG...

 

[Newb]

Thanks for posting the link, Breathe.

I found the presentation by Kuttner quite interesting and I wouldn't be surprised to see such cars succeed in the auto market 15-20 years from now. Good thing is that Kuttner and team realized that battery electric cars are the future, and not hybrids or FCVs. The "architecture" of the cars he's presenting might seem strange but he's actually right that this quad-like shape might get more popular in the future. The Renault Twizy, for instance, is quite popular here in Europe. In Germany it was best-selling "electric vehicle" in 2012 (it's actually not considered a car, but rather a quad).
Here's some pictures of the Twizy: The Renault Twizy Visits New York, And Soon US Dealerships? | Inside EVs

The Toyota i-Road Kuttner is refering to as well, is about to hit the roads soon, too. So, again, I think it's not improbable to see Kuttner's cars on the road some day - maybe even as google or apple cars?

 

[ElSupreme]

The Model S is simply too heavy to ever be a cheap as the mass market needs it to be. It's a big heavy car and it will always have a certain cost per pound.

I can tell you this isn't really the case. And in many ways works much the opposite. Take bicycles the lighter they are the more expensive they get. My road bike probably weighs 1/2 to 1/3 of what you will buy in a Target. And it cost about 50x as much as a bike you buy from Target.

Cheaper materials often are so cheap that using too much, but staying safe is cheaper than cutting out all the bloat.

I think we will all agree that lighter is better (except when in impacts with much more massive objects, which is another discussion) for vehicle dynamics. And by all means a great goal. And the Model S is a little porky. But with almost entirely Aluminum construction it was designed to be 'lightweight'. It just has too much stuff, and too much size to really be light. And without cutting stuff out your not going to make drastic weight gains.

 

[PeterK]

I have a family and would prefer a vehicle with more passenger space than the Model S. So for me, the Model X is better. On the other hand, if I'm going somewhere solo, then my road bicycle is often my preferred mode of transportation.

Have you test driven a Model S? It has tons of useful space. I have carried five kids with winter clothing for a long weekend (no ski equipment but one brought a guitar) on a 260 mile drive comfortably. With the seats folded down I've put full size bikes inside. It's got as much capacity as some SUVs.

 

[GSP]

I'm a big fan of Tesla Motors and I pick up my Model S - P85+ on May 28, 2014. I expect to be very happy with it, and I plan to do as much as I possibly can to help Tesla sell more.

However to achieve Tesla's stated goal of making a mass market electric car at prices that everyone can afford, the approach of the Model S. and everything I have heard about the Model E is not the best approach. The Model S is simply too heavy to ever be a cheap as the mass market needs it to be. It's a big heavy car and it will always have a certain cost per pound.

Now I don't know exactly what is planned for the Model E, but I do know that it will be extremely difficult to simply build a scaled down Model S, at a price that everyone can afford. This will be true even if volume goes up a lot.

Here's a video by Oliver Kuttner. He's the leader of the team that won the 5 Million Dollar X Prize for a car that got over 100 MPG. I belive Kuttner's approach to be much better than anything I have heard about the Model E. Kuttner's car can be made very safe using techniques derived from race cars, and it can be much cheaper than anything currently on the road. By the way Kuttner is a big fan of electric cars even though his X Prize Winning Edison 2 was gasoline powered.

It's 30 minutes long and very good.

This recipe for failure has been tried and proven many times. You are welcome to add yet another statistic to support this if you wish to invest in it. The public will not pay an EV premium for a "punishment car."

Tesla has shown us the formula for success. This formula has worked for many new industries over the centuries, such as electric power and light, railroads, telegraph, telephone, television, cell phones, video recording, fax machines, and the first automobiles.

Elon Musk outlined this in his "secret master plan" blog at teslamotors.com at the very beginning.

GSP

 

[ItsNotAboutTheMoney]

I can tell you this isn't really the case. And in many ways works much the opposite. Take bicycles the lighter they are the more expensive they get. My road bike probably weighs 1/2 to 1/3 of what you will buy in a Target. And it cost about 50x as much as a bike you buy from Target.

Cheaper materials often are so cheap that using too much, but staying safe is cheaper than cutting out all the bloat.

I think we will all agree that lighter is better (except when in impacts with much more massive objects, which is another discussion) for vehicle dynamics. And by all means a great goal. And the Model S is a little porky. But with almost entirely Aluminum construction it was designed to be 'lightweight'. It just has too much stuff, and too much size to really be light. And without cutting stuff out your not going to make drastic weight gains.

I think this is an important point and it fits with Elon Musk's whole business philosophy: figure out what you need to have a good product and then try to do it at low cost. That why he hates concept cars that'll never make it to market: it's a waste of time and money. Pricing and volume go together, so when you add a dollar in manufacturing cost, you're adding more than a dollar in price. When you use materials that make scaling difficult, you add cost. Induction motor, aluminum body, mass-produced cell form factor, engineering use of cheap cells, swappable battery form factor, flexible assembly lines, flexible robots, in-house parts manufacturing, pay-once public charging. It's all about synergies of cost and volume.

That is, coming back to the point of the thread: very light is a nice idea, but quite light with millions of sales is better.

 

[Tasdevil]

Exactly. With an EV, the worst part about weight is performance/handling--not efficiency. As you mention, with more mass, you have more energy to recapture using regen.

Does this mean a trailer(and the extra weight it adds) won't be too taxing on range?

 

[jerry33]

Does this mean a trailer(and the extra weight it adds) won't be too taxing on range?

No. You add the rolling resistance of additional tires and mess up the aerodynamics. It will be taxing on range.