evnow
Well-known member
Let us get back to i3 ...
...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...
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..."
Click to openJay Cole said: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.
surfingslovak said: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.
palmermd said:And the Leaf is a different class of car than the i3. That is like saying the 330i weighs less than the 540i.
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.TonyWilliams said: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.
SanDust said: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.TonyWilliams said: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.
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.
surfingslovak said: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.
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.palmermd said: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.
surfingslovak said: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.palmermd said: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.
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.TonyWilliams said: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.
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.surfingslovak said:but I wonder how the wheel size is going to play into this.
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 said:The same car made without the aluminum frame and CFRP body weighs 250-350 kgs more.
SanDust said: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.surfingslovak said:but I wonder how the wheel size is going to play into this.
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 said:The same car made without the aluminum frame and CFRP body weighs 250-350 kgs more.
evnow said: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.
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.TonyWilliams said: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.
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