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Kamis, 15 September 2016

The 2014 (60Ah) i3 REx vs The 2017 (94Ah) i3 REx

255 miles of combined range? This range estimator is probable a little more optimistic than real life, but I definitely believe 200 miles is possible with the new 2017 i3 REx. 
What a difference three years makes.  I was able to secure one of the first 2017 BMW i3 REx cars that made its way into US dealer inventory, compliments of Chris Chang, Sales Manager at BMW of Bloomfield here in New Jersey. The vehicle is mostly the same as my 2014 i3 REx, the one big exception is it has the new 94 Ah battery cells, which increase the overall battery capacity from 21.6 kWh to 33 kWh without increasing its physical size. That was necessary, since this isn't a redesigned i3, so the battery modules had to fit in the existing battery tray.
The 2017 i3 REx in Fluid Black next to my "Moloughney Red" wrapped 2014 i3 REx
As much as I wanted to check out the moonroof option that this car had (finally the moonroof is available in the US!), there is no denying the single most important improvement I was interested in was to find out how much more range the new model has. The EPA range rating for the 2017 i3 REx is 97 miles per charge, and BMW claims 180 miles of total range when combined with the added miles from the range extender. The full 2.4 gallons of gas is now available for the REx. Previously it was software limited to only 1.9 gallons so the vehicle would qualify as a BEVx vehicle. My 2014 i3 REx has an EPA rating of 72 miles per charge, and BMW claimed a total range of 150 miles including the range extender miles. So the new i3 REx should offer about 35% more all-electric range, if the EPA test results are accurate. One thing to note is the auto manufacturers do the range testing in house, and reports it to the EPA. I think many people are under the assumption that the EPA tests the cars, and they do not. Manufacturers have been known to "massage" these numbers to fit their needs.

Range Testing

I wanted to perform three tests. The first was to fully charge the car and drive it easy. I didn't hypermile, but I took it a little easier than I usually drive. It was 83 degrees, which is favorable for good range, but I did have the A/C on the entire time. I drove in Comfort Mode because that's pretty much the only mode I ever drive in. I took a combination of highway and secondary roads and basically drove the speed limit with moderate acceleration from stops.

After 100 miles of driving, the car still had 26% state of charge and was estimating an additional 37 miles available. I've driven my i3 long enough to know how far it can go, within a couple miles, and I'm sure if I were driving my i3 in those same conditions it would have gone about 72 to 76 miles before the range extender would have needed to turn on. This new i3 REx easily beat the 35% range increase expected by the EPA range rating. In fact, based on these results I think it would be hard for me to get less than 100 miles per charge even if I tried. So that's what I did for the next test.

This time I was going to drive it harder. Not Autocross hard mind you, but I'd punch it from all the stops, drive 75 - 80 mph on the highway and not concern myself with using the regenerative braking to their fullest advantage. Basically, I'd drive like I was late to an important meeting. Halfway through, I realized my efforts weren't making much of a difference. At 50% SOC I had driven 62 miles and the range estimator still showed 62 miles to go. I did noticed that the gas range estimate had dropped from 85 miles to 75 miles though, even without using any. That's because my driving efficiency was much worse than it had been on the first 100 mile drive.

Seeing how I was still on my way to 120+ miles of range, I stepped up my assault on the tires, and really thrashed the car around a bit. It worked, and I further reduced my efficiency. I finished up this 100 mile trip with only 13.5% SOC and estimated 16 miles remaining. I was able to reduce the single charge range by 21 miles, but I couldn't manage to get less than 100 miles of range, which was my goal. In my opinion this is great news. Honestly, I don't know how this car is rated at 97 miles per charge; that's nearly impossible to attain unless it's being operated in cold weather or perhaps being driven at a very high rate of speed. I'm sure once the winter months roll in and the temperature drops it won't be hard to get less than 100 miles of electric range. However in moderate temperatures, I think most people will always be in triple digits. Based on the experience with my car, I'm guessing this new i3 REx will probably average about 85 to 90 miles of all electric range in the winter. My car only averages about 60 to 65 miles of electric range when the temperatures are below 30 degrees Farenheight, therefore 85 to 90 miles sounds about right for this new, longer range model.
Even with trying to get less than 100 miles, I still managed 100 plus an estimated 16 miles remaining. 

The REx Test

The final test was to see if the range extender performance was any different. Much has been made over the fact that the i3 REx can enter Reduced Power mode, and slow down under certain strenuous driving conditions. So I depleted the battery, drove it for 50 miles and made sure to take it up some hill climbs at highway speeds. The first thing I noticed is the range extender operates the exact same way as it always has. It doesn't turn on until the battery state of charge reaches 6.5%. The "Hold State of Charge" option is still disabled here in the US, so if you want that feature, it will still have to be unlocked by coding the vehicle, as before. There was some speculation that the automatic turn on point of the REx might be at a higher SOC with the new model, but I can confirm that's not the case. However, there were two observations that I noticed that were positive.

First, the range extender seemed quieter from inside the cabin. In my car, the REx motor is pretty quiet and unnoticeable until it kicks into it's highest output mode. At that point you can definitely hear the scooter engine revving up high from underneath the rear seats. It's kinda like you're being chased by lawnmower. On long highway trips it will operate at its highest level for most of the journey and the noise is noticeable. I'll usually turn the radio up a notch to cancel it out. With this new car, driving at a constant 75 mph to 80 mph the motor seemed much quieter than it does on mine. My wife was with me for part of this test and she also noticed. She actually asked me if the REx was even running. It seems to me that BMW improved the REx soundproofing. It does sound just as loud as before from outside the vehicle, but it's definitely quieter on the inside.

Secondly, (and I've reached out to BMW for confirmation on this but haven't received a response yet) it does seem like the REx motor has been tuned for a slightly higher output. I took the vehicle on highway roads that I drive on regularly, and have on occasion done so when the REx was operating. The range extender was able to hold the state of charge higher, and under more strenuous driving conditions than my 2014 REx can. There's one particular long incline that I drive every day. With my car, if I start at the bottom with 6% SOC and drive 70 mph up to the top I'll deplete the battery to about 2.5%. I did this same test with the 2017 car and I reached the top of the climb with 5% SOC remaining. I repeated the climb with the same results. I also noticed that I could drive at about 75 mph on flat ground and maintain the 6% SOC. My car can maintain the SOC on flat ground with a constant 70 - 72 mph, but not any higher or the charge will slowly deplete.

I know the 6.5% buffer is now larger, because it's holding 6.5% of 30 kWh instead of 6.5% of about 19 kWh, so that extra energy is definitely helping, but to me it appears that the REx motor has a higher output for the 2017 model. The REx motor in my car is rated at maximum power output of 28 kW. I wouldn't be surprised it we find out the power has been increased to about 33 kW, but I don't have any official confirmation on that. I'm just going on what I've experienced with the previous REx cars and how this new one compared to it. Another hint that I may be correct is the REx is now rated at 35 mpg, down from the 39 mpg which the previous models were rated at. I don't think the extra 170 lbs alone would cause a loss of 4 mpg. I believe it working harder now to produce more energy, which was I'm guessing was achieved through a software adjustment.
After driving 42 miles on the highway I still had 70.5% SOC and an estimates 93 miles or range remaining. My 2014 i3 REx doesn't even go 93 miles per charge!  The range of the 2017 is a substantially greater than previous i3s, even more than the EPA rating would seem to advertise.  

Faster Charging With A New Profile

Previous model year i3s were capable of charging at 30amps which, at 240 volts, gave a maximum draw of 7.2 kW. The new i3s can accept 32 amps which translates to 7.4 kW. Not a huge difference, but it can help if you're waiting for the car to charge to a certain SOC so you can unplug and drive. I should note that most public charging stations are limited to 30 amps, so it won't make a difference on those units. However at home, I have charging stations that can deliver 32 amps so I was able to monitor the difference. My car usually accepts 7.1 to 7.2 kW (depending on the voltage supply) but this new i3 was consistently drawing 7.3 kW to 7.4 kW, so I can confirm the onboard charger upgrade.




















The charging profile of my 2014 i3 REx is on the left, and the 2017 i3 Rex is on the right. 
Both charged from 6.5% to 100%. The 2014 car charges fully in about 3.5 hours and the 2017 in about 4.5 hours.

I did observe something interesting while monitoring the charging profile of the new i3. Instead of the charge rate gradually tapering off as the SOC reached 90%, and slowing down for the final 40 minutes of charging, this car took the maximum rate nearly right up to the end of the session. I charged it three times to monitor this and it behaved the same way all three times. I've never observed this on any other EV. Normally, the vehicle slows down the charging rate considerably as it approaches the end of the session to slowly balance the cells. This takes place once the vehicle is over 90% and the final 5% to 10% of charging takes much longer than charging at lower SOC. That's not happening with this vehicle. It only slows down slightly, and only for a couple minutes at the very end. The charging rate doesn't gradually lower until it shuts off, it more closely resembles falling off a cliff. Interesting.

Finally, a Moonroof

This is fully opened
The moonroof is a new option for the US. It's been available all along for i3s outside of North America, and now it's available here also. The moonroof is a $1,000 option and is a split version, having two openings separated by a solid center section. Each opening has its own manually-operated sunscreen, but the moonroof itself is one piece, and slides back with a push of a button. However it only opens about eight inches, slightly more than half of the actual opening in the roof. It's not even large enough to stick your head out of it - not that you would want to do that; but the point is, it's a small opening. The moonroof does accomplish two things, though. It allows more light in the cabin, giving the feeling of it being more open. It also allows you to eliminate side window buffeting by simply tilting the moonroof open.



Available Battery Capacity - Surprise!

BMW states that the new battery is 33 kWh, and 27 kWh of that is usable. That's only 81.8%  of the total pack, much less than the ~90% they allowed to be accesses on the 60 Ah battery pack. When I read that I wondered if it was perhaps sign that the new 94 Ah cells were less tolerant to deep discharge than the 60 Ah cells were, so BMW was going to be conservative with them. So when I fully charged the battery after the first 100 mile test run, I checked the hidden diagnostic menu and to my surprise it was showing a full 30 kWh accessible. So BMW is allowing access to roughly 90% of the overall pack, just like they do with the 60 Ah cells. That explains the extra range I've witnessed but it doesn't explain why BMW's official stance is that there is only 27 kWh accessible. Perhaps it's for battery capacity warranty claims?
While the "Batt.Kapa.Max" isn't an exact measurement of the available capacity, but it is very close. Close enough to prove there's much more than the 27 kWh that BMW claims is available.


Gained Some Pounds

The only negative I've found is that the new battery is heavier, and adds 170 lbs to the curb weight (3,064 lbs to 3,234 lbs). This does effect performance a bit. The car doesn't feel quite as responsive as my 2014 does. Without testing the performance times, I'd say it's probably close to a half a second slower from 0 to 60 mph. Handling didn't seem quite as crisp as mine either, but that might not be this car's fault. It has the 19" turbine wheels, and my i3 the 20" wheels with the sport tires, which are wider and have a larger contact patch. I also recently lowered my car with sport springs from H&R which have improved the handling, so it's not fair to compare the handling to my car.

My i3 before and after installing the H&R Sport springs. It dropped the car 1" in the front and .8" in the rear.
The other performance change I noticed is the regenerative braking seems to be blended in differently. When driving slowly, it seems pretty much the same as my car does. However at higher speeds the car will coast more when releasing the accelerator. The regenerative braking doesn't initially come on as aggressively as is does on my car. It will get progressively stronger if you continue to coast, but initially upon releasing the accelerator, the car freewheels a lot more than previous versions do. I like this for highway driving, as freewheel coasting improves efficiency. If you slightly depress the friction brake pedal, the friction brakes aren't used, instead the car used first uses only regenerative braking, until you depress the brake pedal harder.

Summing Up

After a couple days and driving over 300 miles I feel it's safe to say that I believe most people will find the average usable range greater than the EPA rating of 97 miles per charge. I almost wonder if BMW purposely underestimated the range a bit in an effort to under-promise and over-deliver. On my 2014 i3 REx, I've found the range to be pretty close to the EPA rated range of 72 miles per charge. I do average a few miles more than that during the warmer months, and about 10 miles less per charge during the winter when it's cold. But this new i3 has unexpectedly trounced the EPA range rating by a healthy margin. I think most people should average well over 100 miles of pure electric range on these vehicles. The range increase will undoubtedly push some people deciding on whether to go BEV or REx into the BEV camp. I know if I were buying one today I'd go BEV also. Getting this kind of range with the REx, I'm certain 125 to 140 miles per charge would be easy to attain with the 2017 BEV. That, combined with the ever increasing CCS DC fast charge networks, would really be all I need for all my driving needs.










Thanks again to Chris Chang and BMW of Bloomfield for providing me with the use of this car for three days of testing.

Jumat, 17 Juni 2016

2017 BMW i3 Specs Revealed With Some Surprises

Fluid Black as pictured and Protonic Blue Metallic will most likely be very popular colors in 2017
While many of the changes that the 2017 BMW i3 will be getting have already been announced; such as the availability of the anticipated 94 Ah battery cells, the new Protonic Blue color and a moonroof option, I've now learned there are also more subtle changes in the US for the new model year.

First, and most interesting, is the revelation that BMW will indeed continue to offer the i3 with the current 60 Ah battery, offering a lower range and lower cost i3 alternative. This is something that I don't believe has been reported on any other EV news site to date. I speculated that BMW would do this back in March, when I wrote this post dedicated to the topic. BMW hasn't made any statements regarding offering two battery options, and made no mention of it in the the official press release of the 2017 i3. Still, my sources tell me otherwise.

The 60 Ah i3 will only be offered as a BEV; the range extender will not be an option. BMW will hold the price and offer it for the same $43,395 ($42,400 plus $995 for destination and handling) as the 2016 i3 sells for.  The 60 Ah i3 will keep the same packages as previously offered. Mega World is the standard model with Giga World and Tera World serving as the upgrade packages. The 60 Ah BEV offering will allow customers that don't need the extra range a way to save some money.
The 19" BMW i Star Spoke 427 style wheels (pictured above) will remain the standard wheels for the 60 Ah BEV i3 in 2017. They will however not be offered on the 94 Ah i3. For the 94 Ah i3's (BEV or REx) the 19" Turbine 429 style wheels that were previously only offered as an option in the Giga World package will be standard. The 20" Sport wheels are still optional, and cost the same $1,300 as in previous years  
Personally I don't see a big demand for the 60 Ah model. It's only $1,200 less than the new 94 Ah i3 and will have a much shorter range at 81 miles per charge compared to 114 (est) for the 94 Ah i3. Forty percent more range for only $1,200 makes the decision a no-brainer in my opinion. So why is BMW even bothering to offer the 60 Ah battery anymore? My guess is mainly for fleet sales. They'll probably offer up a very competitive lease deal for fleets, like they recently did for the Los Angeles Police department. It's also possible that they have excess supply of 60 Ah battery cells that need to be used. BMW no doubt had to guarantee to purchase a certain number of cells from Samsung when they negotiated the original supply contract. Perhaps they didn't sell as many i3s as planned, and still have a few thousand 60 Ah packs to use, however that's pure speculation.
The 94 Ah 2017 i3 will finally have a moonroof option. It will be available for $1,000 on both BEV and REx cars. It will not, however be offered as an option on the 60 Ah i3.
The 94 Ah BEV will list for $44,595 and the REx will now cost $48,350. Comfort Access and the Universal remote garage door opener are standard on the 94 Ah i3. To get them on the 60 Ah i3, you need to upgrade to the Giga World package. So that alone helps to close the $1,200 gap in pricing between models. The much anticipated moonroof is available as an option on both models for $1,000, but it's not available on the 60 Ah model. The 94Ah i3 has a new standard trim called Deka World. With the standard Deka trim, as mentioned above, the Turbine 429 style wheels are standard, as is the Deka Dark cloth, an interior not previously offered in the US although it had previously been offered as the standard interior on European i3s.
The new standard Deka World is called "Atelier" in Europe. It's a combination of dark gray and black cloth, with BMW i blue trim. 
There are then three optional "Worlds" to choose from, instead of the two in past years. Mega World, a $1,400 option, offers the 19" Turbine 428 style wheels and the Mega Carum Spice cloth interior.  Mega World doesn't  offer an interior upgrade, like Giga and Tera Worlds offer. Instead it's actually just a different color cloth with no upgrades in the dashboard trim. One potential problem I can see with this, is that Mega World is the standard interior on the 60 Ah i3, and it doesn't offer the 19" Turbine 428 style wheels. So "Mega World" isn't the same on all i3s, you need to know which battery the car has to know what wheels it comes with. It's standard on the 60 Ah, but optional on the 94 Ah, and has different wheels depending on the battery. That's certainly going to give some client advisers and customers a headache.
The Dark Oak wood trim is a new offering on the i3. It is available in the Giga or Tera World packages and customers get to choose if they prefer this, or the lighter Eucalyptus wood which was previously the only wood trim offered.
The next level up is Giga World which costs $1,800. Giga World also upgrades the wheels to the Turbine 428 style wheels but also upgrades the interior. In previous years, Giga World upgraded the wheels from the standard 427 Star Spoke wheels to the turbine 429 style wheels. Now for 2017 it upgrades from the standard 429 style wheels to the 428 style wheels which is also a bit confusing, especially since a Giga World 60 Ah i3 comes with the 429 style wheels - different than a Giga World 94 Ah i3! The interior for a 94 Ah Giga World i3 is the same as it has been in past years, and the same as it is on a 60 Ah i3 for 2017. The only change is the customer now has a choice of the light Eucalyptus wood trim, or the new Dark Oak Wood trim.
The Tera World interior remains the same. The only exception is there is now a Dark Oak Wood trim option. My i3 pictured above has the Eucalyptus wood trim. Customers now have their choice of which wood they prefer.
The top of the line World is still the Tera World, and it's a $2,600 option. It has the exact same offerings as the Giga World, except it has a full leather interior. It's the same Dalbergia Brown color as in previous years and what I have in my i3.

As for exterior colors it appears that only Capparis White is standard, and any of the other five other colors will cost an additional $550. Those include: Fluid Black, Ionic Silver Metallic, Protonic Blue Metallic, Platinum Silver and Mineral Grey. Also of note is the new Protonic Blue Metallic will not be available on the 60 Ah i3.
The new Protonic Blue Metallic will likely be a popular choice. However you'll have to order the 94 Ah battery if you want this color because it's not available on the lower cost 60 Ah i3. 
That's all I have for now. Based on my research I believe everything above is correct. However BMW hasn't formally released these details and it's possible that I didn't get everything 100% correct. I'll follow up and make any corrections necessary if that proves to be the case.

Kamis, 12 Mei 2016

Here's Why an i3 Battery Upgrade Currently Doesn't Make Sense

The 2017 i3's 33.4 kWh battery pack is the same physical size as the current 21.6 kWh pack. BMW purposely designed the battery tray this way, so that future battery upgrades would be possible. Allowing the i3's battery to be upgraded was always BMW's plan.
The concept of upgrading an electric vehicle's battery pack is certainly not a new one. In fact, it's something that many EV owners have been vocal about wanting to see offered. So the news that BMW will begin a battery upgrade program for their current i3 owners is good indeed, even if it may be something that isn't really necessary, or practical - yet.

The big news in BMW i's May 2nd press release was, as expected, that BMW would be upgrading the i3's battery cells from 60 Ah to 94 Ah. This means the 2017 i3 will have an EPA range of 114 miles, up from the current 81 miles per charge. These new battery cells are physically the same size as the currently used cells, but can hold 50% more energy and are only slightly heavier. About halfway down the press release, this interesting bit was stated:

Retrofit Program: The Battery Can Be Exchanged Optionally

"The Main focus at BMW i is on sustainability. The consumer is given the assurance that his (her) BMW i3 can be adapted to the latest technical developments in a resource-saving way. This is safe-guarded by the flexible LifeDrive vehicle architecture. The BMW i3 is the first automobile in the premium compact segment in the world to have been designed from scratch as a purely electrically powered vehicle. This design also includes retrofitting new battery technologies.


With the introduction of the new 94Ah battery, BMW gives BMW i customers the opportunity of retrofitting their purely electric BMW i3 (60 Ah) with the new 33 kWh battery as part of the a high-voltage retrofit program. This program is available in select markets. The 22 kWh batteries traded-in by customers are used to build stationary storage battery modules thus starting their second life. This effectively proves how sustainable BMW i technology is across its entire production and service life cycle."

I highlighted "select markets" because it appears that BMW AG is allowing its regional offices to decide if they want to participate in the retrofit program. BMW of North America and BMW UK have both declined to participate at this time. It's believed that is because the cost of the retrofit is high, and since the cars are still relatively new, they believe few customers would elect to upgrade. While there hasn't been any official cost announced for the upgrade yet, I've had people in European countries that will participate contact me, and tell me they were quoted roughly $8,000 US. I've also seen people in i3 Facebook groups discuss a number similar to that, so I believe $8,000 is likely accurate.



This is actually pretty close to what I predicted an upgrade would cost, and why I've previously said it will be very hard for BMW (or any manufacturer for that matter) to offer a reasonably priced battery upgrade as new, better battery cells become available. There's a reason why no OEM has offered a battery retrofit program for a currently-available model like this. The exception being Tesla, which has offered a battery upgrade option for their Roadster owners to consider, however it costs $29,000 and was offered three years after Tesla sold their last Roadster. Tesla does not offer battery retrofit upgrades to vehicles that are currently in production, namely the Model S and Model X. Roadster owners were generally underwhelmed by the upgrade offer, and while it's unclear how many took advantage of the program, it's most certainly a very small number.

The only other upgrade comparison worth noting is that Nissan will allow LEAF owners to replace their pack with the same size 24 kWh battery for $5,499. They won't however, allow a customer with a 24 kWh to upgrade it to the new LEAF 30 kWh battery. This isn't a battery upgrade program since Nissan only gave customers the option to replace their battery with the same one, albeit new pack. Offering a battery pack upgrade isn't an easy thing to do, it's not just a matter of swapping the modules with the new cells. There's plenty of reasons why BMW is the first OEM to offer this on a currently available model. In fact, Transport Evolved covered this topic in depth with this post a couple months ago.

So BMW's retrofit program is indeed something unique, and hopefully something the other OEMs copy. The fact that BMW uses the traded in battery packs to build stationary energy storage modules opens up another question: Who's going to use them? Will BMW sell them to a third party or will BMW refurbish them in house and sell the battery storage unit themselves, ala Tesla's Powerwall?  I'd love to upgrade my battery pack in about three more years when I have 130,000 miles on it, and get my old battery back from BMW, refurbished and ready to be used in my home. BMW hasn't elaborated on exactly what they plan to do with the "stationary storage battery modules" made from the traded-in packs, but this is an option I believe and may very well end up being what they do.

Personally, I like the idea of getting my car's old battery back to use in my home. It would really expand the sustainable life-cycle model that I'd like to employ. It would also be a cool conversation piece, especially when someone asks me sarcastically, "Where do you think those EV batteries go when you replace them?" Intimating that they will end up in a landfill, leaking toxic acid which is a common misconception about high voltage lithium ion batteries used in EVs. I would be able to answer, "After powering my car for 130,000 miles, I replaced the battery pack with a new one that now allows me to drive twice as far as the original pack. I then took the original battery pack and put it in my basement where it will be used for about a decade, storing energy generated from my solar array, so now I'm always driving on sunlight, whenever I plug in to charge."
So why doesn't battery retrofit make sense now?

While this sounds great, the truth is it's still a little premature to get excited about the retrofit program. The i3 is only about two years old, and even the earliest i3s delivered in Europe aren't even close to the point where they need a battery replacement yet. Here in the US we just passed the two year anniversary of the first i3 delivery this week. It just doesn't make sense to replace an EV battery which is only two or even three years old, especially since the vast majority of i3's are leased. I believe this is why BMW of North America and BMW UK both decided against offering the battery upgrade program at this time. It's not that they don't think battery retrofit is a great idea, it's just not time yet.

I took delivery of the first i3 REx in the US on May 25th, 2014, so I've owned my i3 for almost two years now. I have a little under 50,000 miles on the odometer and so far my battery has about 94% of its original capacity. I have one of the highest mileage i3s in the country and still have 94% battery capacity; why would I, or anyone for that matter, want to buy a new battery pack now? As I mentioned above, I definitely plan to upgrade my battery at some point, but I first want to get value out of the pack I already paid for. If I continue driving at the same rate I am now, which is 25,000/yr, then in three more years (2019) I'll have 125,000 miles and will probably be ready to upgrade.

Coincidentally, in 2019 BMW's battery supplier Samsung SDI, is scheduled to release their next generation of automotive lithium ion battery cells, which will be 125 Ah. The cells BMW will be using in the 2017 i3 are 94 Ah, replacing the 60 Ah cells I have in my i3. I'll most likely skip the 94 Ah generation and upgrade directly to the 125 Ah cells once they are available, and that's exactly what I expect most 1st generation i3 owners will do. Upgrading to the future 125 Ah cells will effectively double the car's range, as opposed to the 40% increase in range the 94 Ah cells are delivering.

That's how battery retrofit makes sense. Paying $8,000 to replace a two year old battery just to add 35 miles of range simply doesn't add up, and it's why most markets won't offer the retrofit program just yet. However replacing a battery with 125,000 - 150,000 miles, after it's been used 5 - 7 years or longer, and doubling the range of the car when it was new does make sense, even at a cost of $8,000 if you plan to keep the vehicle long term. Plus, the cost of the cells will most likely continue to drop, and the replacement pack will probably cost less in three years than it does now, even though you'll get better batteries. I really like that BMW AG is starting the program now, even if it's not likely to get many takers. This will allow them to work out any potential problems, gradually improve the program, and in a couple of years time when the early i3 owners start inquiring about it then BMW will be 100% ready. By 2018 I expect most major i3 markets will be participating in the retrofit program, just as the demand for battery pack replacements begin to rise.