Reverse Engineering BMW i3 – Video


Courtesy of Forbes, we present this reverse engineering video on the BMW i3:

“Engineers from Munro & Associates show some of the innovations in the new electric car from BMW.”

The geeks amongst us will appreciate this video and there’s even a mention near the end that claims BMW makes money on each i3 sold.

Video can’t be embedded, but here’s the link to watch it in its entirety.

Categories: BMW


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32 Comments on "Reverse Engineering BMW i3 – Video"

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More revolutionary that the Tesla? I don’t think so. The safest car on the road? Again opinion. I think Tesla got a higher safety rating. The i3 is well engineered and a great effort from BMW, but it is not the most important car since the Model T? Clearly Tesla has already taken that crown. Every other car manufacturer is now just playing catch up.

Yeah, sorry. The BMW i3 is far more technologically advanced than anything Tesla has. Just because the Model-S has more range, and is faster does not mean it is more technologically advanced. And I think the guy in the video is really more interested in the carbon fiber than the electric drive aspect of the car, when he’s talking about being more important than the Model-T. Which leads me to believe that he thinks all vehicles will someday be made of CFRP.

Apples and oranges. The Model S is technically advanced in ways that are different from the i3.

Which car is more significant? Depends how you measure it. Historically I would have to say that the Model S is more significant, in terms of what it has done to the industry and what it has proven about Tesla’s ability to deliver a vehicle produced in significant quantities.

Even the Roadster, which according to Bob Lutz led directly to the Volt, is probably more significant.

The i3 is an important car for sure. But will it bring about a new era of CFRP? I’m less than sure about that. What does the CFRP life cycle look like? Aluminum can be endlessly recycled. What do you do with CFRP? This affects the resource footprint of the car.

The CFRP life cycle looks horrible. Takes huge amounts of energy to make the CF, and it is not practicably recyclable.

Add to that the relatively small effect of weight reduction (and I am by no means sure that this car is any lighter than it would have been had they used steel or aluminium)on the energy consumption of an EV, and it seems pretty clear that the life cycle profile of this car will be worse than comparable BEVs, and much worse than if they had not used all of this CFRP.

Right. BMW spent >2 billion dollars on a technology that is no lighter or better than conventional steel construction and that cannot practically be recycled despite being domiciled in Germany whose recycling requirements are among the strictest in the world.

There are other reasons for BMW to figure out a way to use CFRP than because it is lighter or better. You don’t have to look any further than this blog to see what kind of brand influence this car is having. And they apparently can certainly charge more for the car.

The End-of-Life Vehicle Directive specifies only that automakers present a plan by which the material could be recycled. It does not require that they demonstrate the likelihood that it will happen. CFRP recycling is possible, but it is economically and environmentally very, very difficult.

Aluminum is very good as well and can indeed be easily recycled but CFRP have recently become recyclable as well apart from transforming it in pellets for heaters. Somewhere in Britain, i think, there was a process developed which uses supercritical carbon dioxide to separate the matrix from the fibers. The fibers obtained with that process are almost as good as brand new ones. So you could just reboost it somewhat with extra fresh fibers, just like Aluminum is reboosted by addition of fresh metal or in both case downgrade to lower demand applications.

It was indeed in Britain but i missed the supercritical fluid. It is propanol, not CO2.
Here is the article I found back:

Again, CFRP recycling is certainly possible, but no one is doing it on anything like an industrial scale. This work is an excellent example of that (still “test-tube scale”).

And while they might be able to eventually make it economically viable, it also remains to be seen whether they can make it environmentally worth doing (“Solvents on steroids”).

The Tesla is going to outweigh just about any non-commercial vehicle it runs into on the road, plus it has miles of crumble zone because its so big.
If BMW made a Tesla sized car with their technology (CFRP) it would be safer and lighter than the Model S.

The Tesla is certainly the most advanced computer-wise on the road. No one else is even close to pushing firmware down to their cars. The i3 is the most advanced in mechanical engineering-wise IMHO.

I wouldn’t be so sure about how light this technology is. It is interesting that, in what is a thinly-disguised BMW commercial, there is no mention of the weight of all of this CFRP nonsense relative to equivalent systems in something like a Leaf.

The i3 is 500lbs lighter than a LEAF and while some of that is due to a 10% smaller battery, the weight savings of the frame is significant. I’d guess the i3’s frame is at least 35% lighter than the LEAF’s.

Indeed! And considering the i3 gets about the same range as a Leaf, says a lot about the efficiency.

The Leaf is also a significantly larger car. When you normalize for the difference in Plan View Area (LxW, a pretty good predictor of curb mass if everything else is roughly equal), the mass difference (of the whole car, not just the body structure) is less than 80 kg (~1272 kg vs ~1350 kg). This is before considering things like the cost difference (potentially more $ for design and manufacturing optimization) and the number of passengers (more passenger capacity = higher GVW, which will necessitate a stouter structure), and of course does not take into account any weight savings in any other areas of the car, like the battery. If we estimate the body structure of the Leaf at ~25% of the curb mass (again, a pretty good rule of thumb for an efficient steel or aluminium unibody structure), that gives us a mass of ~337 kg. In order for the i3 body structure to be 35% lighter, it would have to weigh less than 220 kg. This would be a body structure mass savings of ~117 kg, much more than our generous estimate for the mass savings of the entire vehicle! Two points: This is of course just a… Read more »

While I can’t argue with any of your numbers (nice analysis, BTW), I would add that one of BMW’s main incentives for building the car this way was simply because it will be a sexy selling point for the typical BMW shopper. That’s NOT meant to be a condescending comment about BMW shoppers/drivers; I used to own a BMW and loved it. But compared to Ford trying to sell Truck Guys on the merits of a lighter weight aluminum pickup truck, I think BMW will have a vastly easier time selling this change to their prospective customers.

That’s a really good point. Being a technology/engineering leader has always been a big part of BMW’s brand, and the i series fits right into that image.

From an environmental perspective, though, this car is hardly the state of the art.

That’s a lot of made up metrics there. Bottom line is the i3 is 500lbs lighter, goes the same distance on a smaller battery pack, and is comparable to the LEAF in all internal dimensions (in fact the i3 has a lot more cargo capacity).

Again, it should be lighter – it’s a significantly smaller car!

I’m not trying to say that one of these cars is better than the other in terms of utility, I’m just using the Leaf to get a handle on how much weight BMW really saved with this design. Because in order to overcome the increased CO2 emissions from all of that CFRP, the weight savings would have to be massive.

And there are not “a lot of made up metrics”, just two very good approximations: the relationship between the mass of a car and it’s PVA, and the approximate share of a vehicle’s mass made up by the body structure.

I honestly think that the way BMW did the i3 REx – small motorcycle engine generator – is gonna be a force in the future. There are some shortcomings now, but they’re easily fixed.

For a long time, a 200-mile battery is going to cost more than a 80-mile battery paired with a $1500 range extender (yes, it should be that cheap when produced in quantity). It would combine the benefits of home charging and quick refill on road trips.

+1, that’s what I keep saying. Why buy this expensive huge battery just for those rare occasion long trips?

There are still externalities of gasoline consumption that is not calculated in your assumption.

In the time it will take for the ReX option to drop from about $4k to $1.5k, the price of batteries will also drop. At $100/kWh for cells, 60 kWh is about $7k including battery pack structure. $1500 would buy an additional 13 kWh of battery. But $1500 isn’t end price – you are lugging around that extra weight for the possible chance that you use it. You also have to maintain it. On the other hand adding battery capacity increases power availability and charging rate given the same chemistry. You also reduce stress on the battery given the same usage characteristics. So you get more than range with a bigger battery.

Yeah, while it difficult to say that it makes no sense, since it does make perfect sense to utilize the already existing abundant infrastructure, gas stations, you now have another engine where things can go wrong, and that will need service.
I think I would go with the REX if the car only had 80 miles of range, but once up over 200 mi. it would be unneeded. At least for me. Also if you are really into POE, purity of essence, you would eschew the REX.

Yes when both price and infrastructure are in place that will be true and that may be here sooner than later. For now, I have to agree with the 50-80 mile AER combined with a smallish extender is really practical.

Charging speed doesn’t matter when you have a REx.

I expect batteries to improve in power availability, too, and really all you need is a 10s burst of 10C, which most chemistries can do today.

As your own numbers show, it’ll be really hard for 200-mile pure EV to match 80-mile+REx in price, and even weight is a wash. The question is how much you want that last 5-20% of your driving to be pure EV.

FYI, BMW isn’t charging $4k because that’s their cost. They’re charging that much because it’s an option, and it’s BMW. That’s how they make their money. They’ll seek the same profit margin for a larger battery option when it becomes available.

I don’t care how much range an EV has. If there is no supporting infrastructure then a 200 mile range isn’t much more useful than a 100 mile range. So I’d still rather have the Rex option so I can stop at any filling station and fill up.

The interest of the Rex is indeed a fast and cheap range extension but it is also a diversification of energy source. Especially if it was flex fuel it would mean the possibility to run on electricity, on gasoline but also on bioethanol. This is a serious asset to be able to face any possible scenario. Black out or oil embargo, you can still drive on home made bioethanol or indeed home roof solar pv. The Rex is extending the possibilities in addition to extending the range. In more if you make a cleaver Rex like a direct free piston generator or a direct ethanol fuel cell, it can also be so compact that the question of having one or not doesn’t make more difference anymore then having a spare tyre or not.


I’m pretty sure this has been posted before.

I didn’t realize it was going to be an ad for BMW. Very clever reverse advertising.

Yeah really. Hired guns. What do you expect them to say? Mark Munro is a regional sales manager of Bmw Canada. I wonder if he is related.
I am suspicious too in the sense that the superlatives are all too superlative and the comments seems like those from a Bmw commercial. In other words talking points, make sure to mention this…etc…

The CFRP and all serious attempts at lightening are important but in the end, the I3 is just another 80 mile range, 4 seater EV and as such its not really revolutionary.

I would have liked them to examine why were there problems with the 7.0, 7.2, or 7.6 kw (???) charger(s) both the euro and North American models that had to be reduced to around 4kw until replacements were available. Now that would have been educational.