Official Tesla Model 3 thread

[NeilBlanchard]

Tesla's Model S is tied for the lowest drag (CdA) car sold in the US. It seats up to 7 people. The car it shares the lowest drag with (the gen 3 Prius) seats 5 people.

There goes all these theories of low drag cars being small, impractical, unsafe, and weird. I think Tesla knows how to make the Model 3 low drag, and practical and safe and good looking.

 

[gbarry42]

A data point: The Prius C has more drag than the full size Prius. This was a compromise resulting from making it smaller. So, there's another challenge to small car design.

For weirdmobiles, having skirts that make it look like there are no back wheels: Maybe someone will invent "virtual wheels"--portrayed by an LCD, or liquid crystal paint, e-paper, or flip-disk technology. After all, it's only the looks that need to be fixed. (Alternatively, we could just get used to the looks.)

 

[gbarry42]

As for Model 3 sales and pricing, remember that Tesla's Secret Master Plan, from day one, has been to produce proof of concept vehicles and make as much money as possible while doing so, with the end goal of being able to make an affordable EV whose numbers will change the way we think about powering our cars. So, I'm looking at a different approach that gets as many cars into the hands of the public as possible. Not that that's bad for the bottom line. I do think that until they can produce as many cars as people will want, that they can prioritize the fancier version (in keeping with the S.M.P), but once production catches up, the goal is to make sure the "early majority" demographic--the ones who say, "I'd get one, if it didn't cost more than a..." are able to buy one.

Making tons of money is nice, but for Elon Musk, it's about the Revolution.

 

[GRA]

Tesla's Model S is tied for the lowest drag (CdA) car sold in the US. It seats up to 7 people. The car it shares the lowest drag with (the gen 3 Prius) seats 5 people.

There goes all these theories of low drag cars being small, impractical, unsafe, and weird. I think Tesla knows how to make the Model 3 low drag, and practical and safe and good looking.

Sure, but it won't be as low-drag as it could be, because other issues have equal or greater priority, as is the case with the Model S. There are plenty of people (I'm not one) who consider the Prius/Insight body style too weird to be acceptable, and it's harder to make a smaller car as low Cd as a larger, because you can't shrink the people in them in proportion to their size.

 

[eloder]

Here's some simple Model 3 math:

200 miles / 4.0 miles per kWh (same as a LEAF) = 50.0 kWh usable (55kWh * $200 = $12k)

200 miles / 4.5 miles per kWh (same as a BMW i3) = 44.5kWh usable (50kWh * $200 = $10k)...

One factor to consider is that the TMS will take some power; that may be part of the reason — in addition to larger size and weight and somewhat less efficient induction motor — that the Model S gets relatively poor mileage compared to a LEAF. I'd be surprised and pleased if the Model 3 managed 0.25 kWh/mile at, say, 100 km/hr. I'm hoping for a more modest 0.3 kWh/mile.

Where I take issue with your numbers is the $200/kWh battery price. My assumption is that the "Gigafactory" will get that below $150/kWh when it opens and that it will drop from there. Just guessing, though.

While I don't have hard numbers (other than what's publicly available on Tesla Motor Club), I think it's generally accepted that TMS gives you back more charge than it takes in power to run it in extreme conditions and is negligible in good conditions.

That's part of the reason why Teslas for example only see a 30% reduction in range for highway trips in the winter at 0-10 degrees, versus the much greater 40-50% on a Leaf.

The Model S gets poor efficiency because it weighs nearly a ton more, not because of TMS. Also part of the reason why smart EDs are kings of real-world city efficiency, low weight (smart ED can push 100 miles on its sub-17 kwhr battery at 45mph and below).

 

[evnow]

Tesla's Model S is tied for the lowest drag (CdA) car sold in the US. It seats up to 7 people. The car it shares the lowest drag with (the gen 3 Prius) seats 5 people.

There goes all these theories of low drag cars being small, impractical, unsafe, and weird. I think Tesla knows how to make the Model 3 low drag, and practical and safe and good looking.

S is not a compact and Musk would consider Prius a weird mobile.

 

[mbender]

Just thinking outside the box (-shaped front end of cars) for a second, how much could the Cd be diminished if the front end could "transform" itself at higher speeds into a cone or similar, optimal shape? What is the theoretical minimum for Cd and/or CdA? (0.0512?, 1.65?!)

I'm sure it wouldn't be that difficult to engineer something on the front end of an EV that changes shape to pierce through the air quite a bit more efficiently than even the slickest Model S. Only at highway speeds. As the speed comes back down to 45-35, the 'transformer' would revert to its original normal shape. I don't know how much could be saved doing this, but if it's non-trivial, it seems like it would be worth experimenting with. Maybe something could be done on the back end as well, if that makes a difference as well (as I believe it does).

 

[DanCar]

Just thinking outside the box (-shaped front end of cars) for a second, how much could the Cd be diminished if the front end could "transform" itself ...

A transformation that is coming in 10 years, made possible by driverless vehicles, are trains. That is cars that attach themselves to each other magnetically even at high speeds to diminish drag. For a train the optimal shape is a rectangular box, unless you are the first or last car.

 

[GetOffYourGas]

Just thinking outside the box (-shaped front end of cars) for a second, how much could the Cd be diminished if the front end could "transform" itself at higher speeds into a cone or similar, optimal shape? What is the theoretical minimum for Cd and/or CdA? (0.0512?, 1.65?!)

I'm sure it wouldn't be that difficult to engineer something on the front end of an EV that changes shape to pierce through the air quite a bit more efficiently than even the slickest Model S. Only at highway speeds. As the speed comes back down to 45-35, the 'transformer' would revert to its original normal shape. I don't know how much could be saved doing this, but if it's non-trivial, it seems like it would be worth experimenting with. Maybe something could be done on the back end as well, if that makes a difference as well (as I believe it does).

Interesting idea. Of course, the back of the car is just as important for aero as the front. That's why the Prius/Insight are shaped the way they are - to reduce the turbulent air pocket which the car drags behind it.

https://en.wikipedia.org/wiki/Kammback

High-performance sports cars already have a retractable spoiler which extends at high speeds. Its purpose is quite different - to provide downward "lift" forcing the rear wheels onto the road. But it's an interesting though to extend that concept towards increasing efficiency.

 

[NeilBlanchard]

Drag is mostly generated at the back of the vehicle.

Just thinking outside the box (-shaped front end of cars) for a second, how much could the Cd be diminished if the front end could "transform" itself at higher speeds into a cone or similar, optimal shape? What is the theoretical minimum for Cd and/or CdA? (0.0512?, 1.65?!)

I'm sure it wouldn't be that difficult to engineer something on the front end of an EV that changes shape to pierce through the air quite a bit more efficiently than even the slickest Model S. Only at highway speeds. As the speed comes back down to 45-35, the 'transformer' would revert to its original normal shape. I don't know how much could be saved doing this, but if it's non-trivial, it seems like it would be worth experimenting with. Maybe something could be done on the back end as well, if that makes a difference as well (as I believe it does).

Another example of a low drag car is the Renault Eolab, and it has 3 active aerodynamic elements; an extendable front spoiler, wheel covers that close, and extendable wheel strakes behind the rear wheels:

The Cd without the aero devices deployed is 0.235, and frontal area is 2.0 sq m / 21.53 sq ft. So the CdA is 0.47 sq m / 5.06 sq ft. When they are deployed, the Cd drops to 0.227.

 

[dgpcolorado]

While I don't have hard numbers (other than what's publicly available on Tesla Motor Club), I think it's generally accepted that TMS gives you back more charge than it takes in power to run it in extreme conditions and is negligible in good conditions.

That's part of the reason why Teslas for example only see a 30% reduction in range for highway trips in the winter at 0-10 degrees, versus the much greater 40-50% on a Leaf.

The Model S gets poor efficiency because it weighs nearly a ton more, not because of TMS. Also part of the reason why smart EDs are kings of real-world city efficiency, low weight (smart ED can push 100 miles on its sub-17 kwhr battery at 45mph and below).

As I understand it, the TMS also uses energy to cool the battery in warm weather. And efficiency and range are two different, if related, concepts. Winter range loss due to a cold battery (LEAF) is not really a factor in efficiency (save, perhaps, for the reduction in regen braking). Rather, friction (aero, rolling resistance) and heater use are. Running the TMS will also hit efficiency even if it increases the usable battery capacity and is a net benefit to range, as you suggest.

My concern about efficiency is two-fold:

1) A less efficient car will use more electricity to go the same distance: charging, driving, sitting unused with the TMS running. My interest in this is personal: since my current solar generation and LEAF/house electricity use is a near perfect match at present, a less efficient car might tip me into the red.

2) The actual driving efficiency of the Model 3 will affect how we model range calculations. Will a typical summer highway efficiency be 300 Wh/mile? 280 Wh/mile? 250 Wh/mile? That last would be quite good for freeway cruising; will the Model 3 be able to get that? Once we have an idea about driving efficiency under various conditions we can speculate about the battery size needed to get 200+ "real world" miles.

I'm guessing that the base Model 3 will have a 60 kWh battery. Others differ.

 

[dgpcolorado]

After some speculation to the contrary, based on a single slide in a show by JB Straubel, Tesla confirms that it is still on track to show the Model 3 in 2016 and begin production in 2017:

http://www.greencarreports.com/news/1098830_tesla-model-3-revealed-next-year-production-starts-2017-company-confirms" onclick="window.open(this.href);return false;

We plan to show [the] Model 3 in 2016 and begin production in 2017.

Of course it remains to be seen whether they can keep to the schedule and several things need to go right — notably "Gigafactory" construction and operation as well as the Model X launch and sales — for them to make the schedule on the Model 3 release. The delays in Models S and X production have left some people skeptical.

 

[Stoaty]

After some speculation to the contrary, based on a single slide in a show by JB Straubel, Tesla confirms that it is still on track to show the Model 3 in 2016 and begin production in 2017

I am rooting for Tesla, but believing they will have any Model 3 cars produced in 2017 just doesn't fit with their history of promised release dates not met. The idea that they will sell a million cars total by 2020 is probably pure fantasy... but glad they are aiming high.

 

[GRA]

Drag is mostly generated at the back of the vehicle. <snip>

Another example of a low drag car is the Renault Eolab, and it has 3 active aerodynamic elements; an extendable front spoiler, wheel covers that close, and extendable wheel strakes behind the rear wheels:

The Cd without the aero devices deployed is 0.235, and frontal area is 2.0 sq m / 21.53 sq ft. So the CdA is 0.47 sq m / 5.06 sq ft. When they are deployed, the Cd drops to 0.227.

There is the wee problem that the back seat appears to be suitable only for double amputees, but the extendible aero is interesting. Of course, it would have to be crash-tested in both configurations, and there might be pedestrian safety issues if unretracted at slow speed for some reason (the personal injury class action lawyers will love that one), but worth a try.

 

[dgpcolorado]

I am rooting for Tesla, but believing they will have any Model 3 cars produced in 2017 just doesn't fit with their history of promised release dates not met. The idea that they will sell a million cars total by 2020 is probably pure fantasy... but glad they are aiming high.

Can't argue with that. But my sense, from their statements in recent months, is that Tesla and Musk are keenly aware of the missed dates for the S and X and are determined to use their hard-won experience on those models to improve their timeline projections for the Model 3.

Regardless, I'll be in on the ordering queue as soon as I learn it is open. I'm pretty patient and I can continue to enjoy driving my LEAF in the interim (unlike so many here who heap opprobrium on the LEAF I'm pleased with mine).

 

[GRA]

I am rooting for Tesla, but believing they will have any Model 3 cars produced in 2017 just doesn't fit with their history of promised release dates not met. The idea that they will sell a million cars total by 2020 is probably pure fantasy... but glad they are aiming high.

Can't argue with that. But my sense, from their statements in recent months, is that Tesla and Musk are keenly aware of the missed dates for the S and X and are determined to use their hard-won experience on those models to improve their timeline projections for the Model 3.

Regardless, I'll be in on the ordering queue as soon as I learn it is open. I'm pretty patient and I can continue to enjoy driving my LEAF in the interim (unlike so many here who heap opprobrium on the LEAF I'm pleased with mine).

I think most people heap opprobrium on Nissan, with the LEAF getting the splatter. The car IS reasonably reliable etc., it's just a battery pack design unsuited to the climate in much of the U.S., and Nissan's behavior once that fact was established is responsible for most of the bile. Mind you, that's a lot of bile, and extremely well-earned.

 

[NeilBlanchard]

Rear legroom look fine to me.

Low drag, great looking ... hmmm let's hope Tesla does something similar. And Nissan, for that matter.

 

[N952JL]

I am rooting for Tesla, but believing they will have any Model 3 cars produced in 2017 just doesn't fit with their history of promised release dates not met. The idea that they will sell a million cars total by 2020 is probably pure fantasy... but glad they are aiming high.

Can't argue with that. But my sense, from their statements in recent months, is that Tesla and Musk are keenly aware of the missed dates for the S and X and are determined to use their hard-won experience on those models to improve their timeline projections for the Model 3.

Regardless, I'll be in on the ordering queue as soon as I learn it is open. I'm pretty patient and I can continue to enjoy driving my LEAF in the interim (unlike so many here who heap opprobrium on the LEAF I'm pleased with mine).

I'm so pleased with my Leaf, I bought it off the lease after the lease expired. (Dec 2011 second in GA ordered first but delivered second.)

 

[mbender]

Rear legroom look fine to me.

Any amount of legroom can be made to look OK if the picture is large enough! :lol:

 

[GRA]

OT. Speaking of weirdmobiles: http://www.greencarreports.com/news/1099022_new-stella-solar-electric-car-produces-more-energy-than-it-uses

AFAICT, the frontal crush space appears to consist of the legs and pelvises of the people in the front seats.