Official BMW i3 thread

[evnow]

Let us get back to i3 ...

 

[edatoakrun]

Not much new in the article below, other than succinctly stating the BEVx conundrum:

...we think that BMW could have a hell of a marketing challenge on its hands.

The company has to launch a brand-new electric car while simultaneously explaining that, yes, the ReX is a range extender that will almost double the range of the car--but, no, the i3 in range-extending mode shouldn't really be used for that purpose on a regular basis...

http://www.greencarreports.com/news/1082814_bmw-i3-electric-car-rex-range-extender-not-for-daily-use/page-2" onclick="window.open(this.href);return false;


Well, I gave my marketing suggestion last month, on p 30 of this thread:

I'm trying to think of the I3 promotional slogan. Maybe something like:

"BMW brings you the first Extended Range Electric Vehicle, designed for short trips..."

 

[surfingslovak]

BMW Has Several Hundred Pre-Orders For i3, First Pre-Production i3s Completed

Today at BMW’s Annual Report Press Conference in Munich, Norbert Reithofer, Chairman of the Board of Management of BMW AG, gave us some interesting updates on the status of BMW’s i3 project while projecting what 2013 will hold for the automaker.

“The future belongs to those who dare to venture”, said Reithofer, as ”electromobility will be very much in the spotlight for the BMW Group in 2013.”

BMW Does Some i3 Testing In Public View Earlier This Year
Mr. Reithofer says that the i3's production line is now currently active and has already produced its first pre-series BMW i3s, beginning this past January in anticipation of being on the market “by the end of the year.”

Although not readily available for the public to order yet, the BMW executive also added that, “Several hundred advance orders have already been received for the BMW i3.”

During the conference, BMW again re-iterated that the i3 has an approximate range of 150 km (93 miles), and should weigh 250 to 350 kgs (550lbs to 770lbs) less than a “conventional” electric car.

Given the limited amount of EVs the public might consider as a “conventional” electric car, one has to assume Norbert is referencing the Nissan LEAF. As a point of reference, the LEAF weighs about 3,350lbs, making the i3 tip the scales around 2,600 to 2,800 pounds.

Click to open

 

[palmermd]

BMW again re-iterated that the i3 has an approximate range of 150 km (93 miles), and should weigh 250 to 350 kgs (550lbs to 770lbs) less than a “conventional” electric car.

Given the limited amount of EVs the public might consider as a “conventional” electric car, one has to assume Norbert is referencing the Nissan LEAF. As a point of reference, the LEAF weighs about 3,350lbs, making the i3 tip the scales around 2,600 to 2,800 pounds.

This comparison does not make sense...why not compare it to the Model S weight? It was a nonsensical comparison. There is no conventional electric car. And the Leaf is a different class of car than the i3. That is like saying the 330i weighs less than the 540i.

 

[TonyWilliams]

And the Leaf is a different class of car than the i3. That is like saying the 330i weighs less than the 540i.

Yes, the LEAF is physically in a "bigger" class of car. Both will have predominately the same highway range, IMHO, with an advantage to the BMW. The BMW will cost a LOT more money.

Using the rule of thumb of 6.5% increase in economy per 10% reduction in weight suggests that the 600 pound lighter i3 might be 18% better economy. That translates to 4.7 miles/kWh at 100kmh ground speed vs 4.0 for the LEAF.

The battery is 10% smaller on the i3, therefore I guess about a 8% increase in range. I suspect both have very similar rolling and aerodynamic drag.

The LEAF can do about 84 miles at 100kmh ground speed (4 * 21kWh usable = 84), and my guess will be 91 miles (4.7 * 19.25kWh usable = 91) for the i3.

 

[SanDust]

Using the rule of thumb of 6.5% increase in economy per 10% reduction in weight suggests that the 600 pound lighter i3 might be 18% better economy. That translates to 4.7 miles/kWh at 100kmh ground speed vs 4.0 for the LEAF.

That rule of thumb applies to conventional ICE vehicles. Since an EV can convert stops and elevation loss into stored energy, mass reduction will provide less economy in an EV than you'd expect. My guess would be that reducing the weight by 600 pounds will net you 3 miles on surface roads and 1 mile on the freeway. Another way to say this is that the dead weight loss of 600 pounds is less than 30 newtons. You can pick any speed and it's not going to amount to much.

On the other hand I can see the i3 being more efficient at higher speeds. It's smaller. That's important because while people obsess over the Cd, A is equally important. From what I've read the i3 is also using a setup something like the Volt's, which means it won't be using a simple reduction gear like the Leaf does. This should make it at least 10% more efficient on the highway. At higher speeds when the power needs are great, a 10% reduction is nothing to sneeze at.

 

[TonyWilliams]

Using the rule of thumb of 6.5% increase in economy per 10% reduction in weight suggests that the 600 pound lighter i3 might be 18% better economy. That translates to 4.7 miles/kWh at 100kmh ground speed vs 4.0 for the LEAF.

That rule of thumb applies to conventional ICE vehicles. Since an EV can convert stops and elevation loss into stored energy, mass reduction will provide less economy in an EV than you'd expect.

My quotes did not consider regen for either car. Again, 4.0 and 4.7 miles/kWh are my guesses for the 2014 LEAF and i3 respectively on LEVEL ground at 100kmh. NO REGEN.

On the other hand I can see the i3 being more efficient at higher speeds. It's smaller. That's important because while people obsess over the Cd, A is equally important. From what I've read the i3 is also using a setup something like the Volt's, which means it won't be using a simple reduction gear like the Leaf does. This should make it at least 10% more efficient on the highway. At higher speeds when the power needs are great, a 10% reduction is nothing to sneeze at.

It's shorter, and therefore may not have the aero improvements (Cd) we think. It's also tall and wide, which translates to A not being significantly different than LEAF.

Your improvement of 10% for gearing is just NOT going to happen. The planetary gearbox is not going to be an efficiency improvement over simple gear reduction. Since BMW is not connecting the REx motor to the mechanical drive train, I see no reason for a planetary gear box anyway.

 

[surfingslovak]

The i3 has reportedly achieved 140 miles on the NEDC cycle. The 2011/2012 LEAF returned 109 miles and the 2013 LEAF 124 miles on this cycle. Much like LA4, NEDC likely heavily emphasizes slow city driving. While I would not expect the outside dimensions to be significantly different from the LEAF, the Cd could be slightly better, but it's difficult to say with the data we have. Bridgestone is reportedly working on some wunder tires for the i3. This could buy a few percentage points, but I wonder how the wheel size is going to play into this. Tom mentioned recently that 19" wheels will be standard and 20" wheels will be optional. My guess is 94 miles of range on a full charge under the EPA 5-cycle test, and Tony is likely correct about the freeway range at steady 100 km/h.

 

[TonyWilliams]

The i3 has reportedly achieved 140 miles on the NEDC cycle. The 2011/2012 LEAF returned 109 miles and the 2013 LEAF 124 miles on this cycle. Much like LA4, NEDC likely heavily emphasizes slow city driving.

So, about 12% greater in slow city driving, and I expect 8% improvement in 100kmh steady highway driving.

 

[surfingslovak]

This comparison does not make sense...why not compare it to the Model S weight? It was a nonsensical comparison. There is no conventional electric car. And the Leaf is a different class of car than the i3. That is like saying the 330i weighs less than the 540i.

Didn't the press pit the LEAF against the Volt too? I always thought that this was a very inadequate comparison, which continues to this day. The i3 will be more similar to the LEAF than the Volt, but I believe BMW admitted that they don't consider it to be their competitor. It's a different market segment, with a different set of priorities. I think they will be fishing in the same waters like Infinity with the LE and Tesla with the base Model S.

 

[TomMoloughney]

This comparison does not make sense...why not compare it to the Model S weight? It was a nonsensical comparison. There is no conventional electric car. And the Leaf is a different class of car than the i3. That is like saying the 330i weighs less than the 540i.

Didn't the press pit the LEAF against the Volt too? I always thought that this was a very inadequate comparison, which continues to this day. The i3 will be more similar to the LEAF than the Volt, but I believe BMW admitted that they don't consider it to be their competitor. It's a different market segment, with a different set of priorities. I think they will be fishing in the same waters like Infinity with the LE and Tesla with the base Model S.

As for the weight comparison, they meant that if they would have used conventional manufacturing materials (steel, etc) the same car would have weighed 250 to 350 kgs more. It's not meant to use any other specific car as the comparison. I know this because I have heard this time and time again from BMW i managers. Perhaps the wording was a little unclear this time but that is the message they were trying to convey. The same car made without the aluminum frame and CFRP body weighs 250-350 kgs more.

 

[SanDust]

My quotes did not consider regen for either car. Again, 4.0 and 4.7 miles/kWh are my guesses for the 2014 LEAF and i3 respectively on LEVEL ground at 100kmh. NO REGEN.

It's shorter, and therefore may not have the aero improvements (Cd) we think. It's also tall and wide, which translates to A not being significantly different than LEAF.

Your improvement of 10% for gearing is just NOT going to happen. The planetary gearbox is not going to be an efficiency improvement over simple gear reduction. Since BMW is not connecting the REx motor to the mechanical drive train, I see no reason for a planetary gear box anyway.

The rule of thumb you cited -- a 10 percent reduction in curb weight will reduce fuel consumption by about 6.5 percent -- refers to the increase in MPG you see from mass reduction in ICE vehicles. As such it would most definitely include losses due to hill climbing, acceleration, deceleration, and so forth. If the vehicle can recapture some of what otherwise would be losses through regen, then regen most definitely would change this number. Adding mass to an EV will cut its efficiency but not by the same amount adding mass to an ICE vehicle would.

FWIW a back of the napkin calculation shows that that your numbers for the efficiency to be gained by reducing the weight by 600 pounds can't possibly be right. Reducing the weight gives you maybe 25 Newtons. Even at 65 MPH you'd only need around 750 watts to overcome the additional rolling resistance this would impose. If these 750 watts amounted to 17.5% (.7/4) of the total kW needed at the wheel, then the Leaf would only need 4.25 kW at the wheel when going 65 MPH. That's not reasonable since it suggests an EV range of nearly 300 miles, and in fact we know that exclusive of drive train losses the Leaf needs at least 16 kW at that speed to overcome the forces of drag and rolling resistance.

The i3 is slightly shorter and narrower than the Leaf. Cd is hard to estimate. I'd guess the Leaf has a better Cd.

On the gearing, turning a larger gear with a smaller motor running at efficient RPM is going to be a lot more efficient than turning a smaller gear with a larger motor running at inefficient (high) RPM. Might not be 10% but I'd say that's a good guess at 70 MPH.

Putting all this together, I'd say the i3 might get 4.3 miles/kWh or 4.4 miles/kWh, almost all of which will be due to better drive train efficiency. I don't think the i3 will have more range than the Leaf in real world driving because the increased efficiency will be cancelled out by the smaller battery. Additionally, the mass reduction will make the BMW more fun to drive so it may see more fast starts and less time between traffic lights.

 

[SanDust]

but I wonder how the wheel size is going to play into this.

Wheel size won't affect the coefficient of rolling resistance but it does add mass. Mass, however, has already been accounted for in the infamous 600 pounds.

The same car made without the aluminum frame and CFRP body weighs 250-350 kgs more.

Have they said how much more this will cost? Reducing the weight will make the car a lot more fun to drive but it won't help much with cost, and the initial cost seems to be a big problem for most potential EV buyers.

 

[TomMoloughney]

but I wonder how the wheel size is going to play into this.

Wheel size won't affect the coefficient of rolling resistance but it does add mass. Mass, however, has already been accounted for in the infamous 600 pounds.

The same car made without the aluminum frame and CFRP body weighs 250-350 kgs more.

Have they said how much more this will cost? Reducing the weight will make the car a lot more fun to drive but it won't help much with cost, and the initial cost seems to be a big problem for most potential EV buyers.

They have been saying that the money saved on using a smaller battery because of the lower weight offset the cost of the CFRP. I couldn't find the quote I was looking for(that I have definitely seen) that basically said that directly but this is close enough:

“The Rocky Mountain Institute, a Colorado-based energy-efficiency think tank, has long championed the use of composites like carbon fiber to create super-green “hypercars.” According to the group, “With drastically lighter platforms, propulsion systems can be smaller, lighter, cheaper, more efficient and, ultimately, more cost-effectively electrified.”

The latter point is critical, because batteries are very expensive, too. Dave Buchko, a BMW spokesman, says that the company chose to make its i3 body shell out of carbon fiber because “we won’t need as many battery cells to reach our target 100-mile range. Our solution balances the right weight with battery capacity.”

 

[evnow]

My guess is the weight comparison is with a '11, rather than '13.

Also since weight isn't a big issue at higher speeds, I guess i3 will have virtually the same range as Leaf at higher speeds.

 

[TonyWilliams]

My guess is the weight comparison is with a '11, rather than '13.

Also since weight isn't a big issue at higher speeds, I guess i3 will have virtually the same range as Leaf at higher speeds.

Ya, all my guessing is based on 600 pounds lighter, and 19.25kWh usable with similar Cd and A. The reality is it might be a little bit lighter than the LEAF, with a smaller battery. And cost $40k-$48k. And a Frankenplug.

There's not enough difference on paper to sway me from any of the competitors unless I really wanted a gasoline motorcycle engine. I think that will popular. Plus, I think a lot of BMW aficionados will buy it just because it has a rotating propeller on the hood.

I told my wife about it, and the only thing she said was, "how far does it go?". I said maybe 10% further than a LEAF..... nope, no way !!!!

 

[surfingslovak]

The LEAF can do about 84 miles at 100kmh ground speed (4 * 21kWh usable = 84), and my guess will be 91 miles (4.7 * 19.25kWh usable = 91) for the i3.

Interestingly, the ActiveE went 92 miles with an economy of 3.4 m/kWh at steady 65 mph last spring. If I'm not mistaken, Tom mentioned that BMW wanted the i3 to have about the same range like the ActiveE. I'm quite curious how these projections are going to pan out.

 

[gergg]

Thought this was interesting.

http://editorial.autos.msn.com/blogs/autosblogpost.aspx?post=1318da42-50ca-4f53-8625-b576557aab17" onclick="window.open(this.href);return false;

 

[TomMoloughney]

Looks like the production nose was "leaked"

Also some new shots by Motoring Authority: http://www.motorauthority.com/news/1056476_2014-bmw-i3-spy-shots" onclick="window.open(this.href);return false;

 

[TomT]

The BMW i as art...

http://www.engadget.com/2013/04/08/bmwi-quiet-motion/" onclick="window.open(this.href);return false;