[YWGT3]

https://www.yahoo.com/autos/the-bmw-...175552931.html

[Efthreeoh]

This is a topic MKSixer and I got into a few weeks ago on another thread in the general forum about BMW supplying hybrid tech to a resurrected Karma automobile company. Some of the points made in the Yahoo article I made in my responses to MKSixer. I don't think the i8 is or ever was the car of the future. MKSixer stated he felt the i8 was a paradigm-shifting automobile, but I just don't see it.

My summary response to the question is this: The i8 basically has two drivetrains in it and not much room for more than two people and 5 cubic feet of luggage space. Most hybrids have a compact dual-mode drivetrain and space for people and luggage. Yes, those cars are not high-performance coupes (or 2-door sedans as BMW used to call them) but most of the real estate in the i8 is consumed by its drivetrain(s), which to me is more an engineering exercise than anything else. BMW is going to have to really shrink the footprint of the drivetrain to translate their i8 technology into a real useable automobile that people with normal disposable incomes can consider purchasing. I just don't see it happening without a serious reduction in performance (i.e. make the parts smaller and less powerful), which gets us back to a vehicle such as the Volt and Prius... It could be possible that GM, Toyota, Honda, all started with dual drivetrains, realized the architecture of a realistic car really didn't allow for such a space-consuming drivetrain footprint, and developed the compact drivetrain that is now found in the typical hybrid.

[MKSixer]

I think that this article sums it up nicely. The i8 provides a hypercar drive train for less than 1/6 the price of the lowest offering of that trio.

It provides linear acceleration, an advanced construction/design and many other bits and bobs that are incredible for the amount of money paid, when considered relative to the hypercar trio.

As Efthreeoh stated before, we had a discussion about this very topic (perhaps we could have written a better piece?) and agreed to disagree. I think that the combination of the technologies along with a somewhat attainable price relative to the hypercar trio is a paradigm shift.

As Jezza said long ago, 'If you want to see what will be in an average car in 10 years, look at the new S-Class Mercedes." Similarly, if you want to see the basic concepts needed for the sports car of the future, look at the i8. Perfect, no...exceptional, yes.

Cheers-mk

[YWGT3]

Originally Posted by Efthreeoh

This is a topic MKSixer and I got into a few weeks ago on another thread in the general forum about BMW supplying hybrid tech to a resurrected Karma automobile company. Some of the points made in the Yahoo article I made in my responses to MKSixer. I don't think the i8 is or ever was the car of the future. MKSixer stated he felt the i8 was a paradigm-shifting automobile, but I just don't see it.

My summary response to the question is this: The i8 basically has two drivetrains in it and not much room for more than two people and 5 cubic feet of luggage space. Most hybrids have a compact dual-mode drivetrain and space for people and luggage. Yes, those cars are not high-performance coupes (or 2-door sedans as BMW used to call them) but most of the real estate in the i8 is consumed by its drivetrain(s), which to me is more an engineering exercise than anything else. BMW is going to have to really shrink the footprint of the drivetrain to translate their i8 technology into a real useable automobile that people with normal disposable incomes can consider purchasing. I just don't see it happening without a serious reduction in performance (i.e. make the parts smaller and less powerful), which gets us back to a vehicle such as the Volt and Prius... It could be possible that GM, Toyota, Honda, all started with dual drivetrains, realized the architecture of a realistic car really didn't allow for such a space-consuming drivetrain footprint, and developed the compact drivetrain that is now found in the typical hybrid.

I see your point if you are trying to analogize the concepts with the Prius and Volt. However, the i8 was meant to be an evolution for sports cars. It was never designed with the intent of competing with four door, 4-5 passenger compact sedans with legitimate trunk space.

As for the i8, I still can't get over doing 35.8 miles per gallon and 0-60 in 3.9 -4.0 seconds on the track. Whereas, I averaged 8-10 miles per gallons in the Lamborghini Gallardo and Ferrari F430, all the while producing a ton of carbon emissions, in order to derive similar sporting experience. Furthermore, neither aforementioned vehicles had any boot space to speak of.

In my opinion, while there are other sports car hybrids out there (McLaren P1, La Ferrari, and Porsche 918), not many, if any at this time, can come close to the competitive production cost and pricing of an i8. In this regard, I can appreciate why some believe the i8 is evolutionary and it is where future sports car design and manufacturing is heading toward.

Now if it were a discussion on whether the upcoming i5 is a car of the future juxtaposed to the current hybrid sedan market, I couldn't agree with you more.

[Efthreeoh]

Originally Posted by YWGT3

I see your point if you are trying to analogize the concepts with the Prius and Volt. However, the i8 was meant to be an evolution for sports cars. It was never designed with the intent of competing with four door, 4-5 passenger compact sedans with legitimate trunk space.

As for the i8, I still can't get over doing 35.8 miles per gallon and 0-60 in 3.9 -4.0 seconds on the track. Whereas, I averaged 8-10 miles per gallons in the Lamborghini Gallardo and Ferrari F430, all the while producing a ton of carbon emissions, in order to derive similar sporting experience. Furthermore, neither aforementioned vehicles had any boot space to speak of.

In my opinion, while there are other sports car hybrids out there (McLaren P1, La Ferrari, and Porsche 918), not many, if any at this time, can come close to the competitive production cost and pricing of an i8. In this regard, I can appreciate why some believe the i8 is evolutionary and it is where future sports car design and manufacturing is heading toward.

Now if it were a discussion on whether the upcoming i5 is a car of the future juxtaposed to the current hybrid sedan market, I couldn't agree with you more.

I think BMW (I'll have to review the old press releases), or perhaps just the automotive press, touted the i8 as putting to production a hybrid car that was light weight by using carbon fiber as a major material of the cassis construction and an innovative drivetrain, that would trickle down to more mainstream (BMW) cars (i.e. "the car of the future"). For the i8 to achieve its performance, under the skin it is mostly drivetrain components and leaves little space for passengers and cargo, which if used in a chassis that does provide space for people and cargo, either the drivetrain components have to shrink or the car has to seriously increase in size. Any reasonable assumption would consider that shrinking the components means less power and a drop in performance. Increasing the size of the car means an increase in weight and a drop in performance. It is my opinion that several of the current hybrids are already where BMW's trickle down i8 technology will lead.

If one looks at the "car of the current", meaning something like the Toyota Camry (most popular selling car in the USA), the i8 driveline tech doesn't translate well. The Volt's drivetrain is pretty sophisticated, I'd say more that the i8's since it puts both power conversion technologies (gasoline to kinetic/electric and battery to kinetic) in an efficient and small component package, where as the i8 doesn't. If the "car of the future" is a super-fast small 2-seat sports car, than yeah the i8 can qualify as that car, but in reality people buy cars to transport them and their stuff in an affordable manner, which other hybrids already offer, regardless of the use of carbon fiber.

[MKSixer]

Originally Posted by YWGT3

I see your point if you are trying to analogize the concepts with the Prius and Volt. However, the i8 was meant to be an evolution for sports cars. It was never designed with the intent of competing with four door, 4-5 passenger compact sedans with legitimate trunk space.

As for the i8, I still can't get over doing 35.8 miles per gallon and 0-60 in 3.9 -4.0 seconds on the track. Whereas, I averaged 8-10 miles per gallons in the Lamborghini Gallardo and Ferrari F430, all the while producing a ton of carbon emissions, in order to derive similar sporting experience. Furthermore, neither aforementioned vehicles had any boot space to speak of.

In my opinion, while there are other sports car hybrids out there (McLaren P1, La Ferrari, and Porsche 918), not many, if any at this time, can come close to the competitive production cost and pricing of an i8. In this regard, I can appreciate why some believe the i8 is evolutionary and it is where future sports car design and manufacturing is heading toward.

Now if it were a discussion on whether the upcoming i5 is a car of the future juxtaposed to the current hybrid sedan market, I couldn't agree with you more.

Exactly.

This is one of the reasons that I think that the i8 is the future of sports car performance. My V10 M6 has gotten as low as 7.0 mpg in spirited driving. In the same driving situation the lowest that the i8 has achieved is 24 or so mpg. A nearly 250% improvement in this situation is more than average..it is revolutionary.

Cheers-mk

[MalibuBimmer]

My M4 gets 22 MPG. I do a lot of freeway driving.

I also drove a 2016 B6 last week. It had been driven in to L.A. from Phoenix. It still showed 21 MPG.

On the other hand, my i8 current shows 70.5 MPG. (My M6 was getting around 9 MPG. The i8 is quicker and more fun to drive.)

[Efthreeoh]

So looked at BMW's original press release. And it definitely states the i8 is intended as a redefinition of the sports car, so in that perspective it is impressive. If my memory serves correctly a lot of the automotive articles and maybe BMW somewhat to have tried imply that the i8 driveline technology can translate into a sedan-class vehicle. And this is where I have my disagreement; I just don't see the i8 drivetrain configuration fitting a sedan. And why my position that the i8 is not the "car of the future". Sports car of the future perhaps. Sports sedan of the future not so much.

[MKSixer]

Originally Posted by Efthreeoh

So looked at BMW's original press release. And it definitely states the i8 is intended as a redefinition of the sports car, so in that perspective it is impressive. If my memory serves correctly a lot of the automotive articles and maybe BMW somewhat to have tried imply that the i8 driveline technology can translate into a sedan-class vehicle. And this is where I have my disagreement; I just don't see the i8 drivetrain configuration fitting a sedan. And why my position that the i8 is not the "car of the future". Sports car of the future perhaps. Sports sedan of the future not so much.

This has been the focus of the entire conversation that I had with you both here, and in the other thread.

Conflation into other auto classes is unreasonable. Secondarily, I know that the drive line technology and configuration can translate into more offerings. There is nothing that would stop BMW from using this configuration with larger battery capacity and multiple engine choices in different applications.

Cheers-mk

P.S. Another consideration: If you look at the members who own i8's, you can see that we are alums or currently own some pretty hardcore high-performance cars. If we, in that context, are raving about the i8 perhaps notice should be taken that it is a truly amazing vehicle.

[Aye-eight]

Originally Posted by Efthreeoh

So looked at BMW's original press release. And it definitely states the i8 is intended as a redefinition of the sports car, so in that perspective it is impressive. If my memory serves correctly a lot of the automotive articles and maybe BMW somewhat to have tried imply that the i8 driveline technology can translate into a sedan-class vehicle. And this is where I have my disagreement; I just don't see the i8 drivetrain configuration fitting a sedan. And why my position that the i8 is not the "car of the future". Sports car of the future perhaps. Sports sedan of the future not so much.

Well, let's see if we can figure this out. Put the ICE engine in the front, where the i8 may not have enough "headroom", but a sedan would. Flatten the battery pack Tesla-style, because it's okay to sit a little higher up in a sedan. Split the electric drive train into two hub motors in the rear. Voila.

Or, to test this another way: the Mini already comes with the ICE engine, the gas tank, and all that. Could you put a flat battery pack under a Mini, slightly increase the size of the car, and still fit electric motors somewhere? Surely.

I was at Toyota City in Japan in October. They displayed a hydrogen-powered Mirai, with two high-pressure hydrogen tanks, a fuel cell stack, a battery, a motor running on hydrogen ... There's a lot that can fit into a sedan chassis if you move things around a bit.

[YWGT3]

Originally Posted by Aye-eight

Well, let's see if we can figure this out. Put the ICE engine in the front, where the i8 may not have enough "headroom", but a sedan would. Flatten the battery pack Tesla-style, because it's okay to sit a little higher up in a sedan. Split the electric drive train into two hub motors in the rear. Voila.

Or, to test this another way: the Mini already comes with the ICE engine, the gas tank, and all that. Could you put a flat battery pack under a Mini, slightly increase the size of the car, and still fit electric motors somewhere? Surely.

I was at Toyota City in Japan in October. They displayed a hydrogen-powered Mirai, with two high-pressure hydrogen tanks, a fuel cell stack, a battery, a motor running on hydrogen ... There's a lot that can fit into a sedan chassis if you move things around a bit.

There's a lot components configured within the Toyota chassis but appears that there is still room to spare. Thanks for sharing the pic pertaining to the hydrogen setup. Looks intriguing.

[MKSixer]

Originally Posted by Aye-eight

Well, let's see if we can figure this out. Put the ICE engine in the front, where the i8 may not have enough "headroom", but a sedan would. Flatten the battery pack Tesla-style, because it's okay to sit a little higher up in a sedan. Split the electric drive train into two hub motors in the rear. Voila.

Or, to test this another way: the Mini already comes with the ICE engine, the gas tank, and all that. Could you put a flat battery pack under a Mini, slightly increase the size of the car, and still fit electric motors somewhere? Surely.

I was at Toyota City in Japan in October. They displayed a hydrogen-powered Mirai, with two high-pressure hydrogen tanks, a fuel cell stack, a battery, a motor running on hydrogen ... There's a lot that can fit into a sedan chassis if you move things around a bit.

I'm a huge fan of hydrogen. I think that it is the true future if the infrastructure can be addressed. The layout the Toyota has is very interesting. I would like to see a few more pics.

Cheers-mk

[Efthreeoh]

Originally Posted by Aye-eight

Well, let's see if we can figure this out. Put the ICE engine in the front, where the i8 may not have enough "headroom", but a sedan would. Flatten the battery pack Tesla-style, because it's okay to sit a little higher up in a sedan.(1) Split the electric drive train into two hub motors in the rear. Voila.

Or, to test this another way: the Mini already comes with the ICE engine, the gas tank, and all that. (2)Could you put a flat battery pack under a Mini, slightly increase the size of the car, and still fit electric motors somewhere? Surely.

I was at Toyota City in Japan in October. They displayed a hydrogen-powered Mirai, with two high-pressure hydrogen tanks, a fuel cell stack, a battery, a motor running on hydrogen ... There's a lot that can fit into a sedan chassis if you move things around a bit.

(1) Hub motors is far from a new idea and would really go against one of BMWs design axioms, which is to reduce unsprung weight. A 50+ horsepower electric motor in the rear hubs would absolutely kill the balance of the car with such a varied difference in unsprung weight between the front and rear suspensions. I remember in the late '80's reading about an upstart electric car company out of Denver IIRC that's design did exactly that had 4 50-HP electric motors one in each hub.

(2) Or perhaps, make a T-shaped battery pack out of uniquely deigned battery prism cells for designed-in cooling attributes, and set it low in the chassis in the center tunnel and under the rear seats. Then put a lightweight ICE under the hood with two compact electric motors for propulsion and charging, and all connected together using a complex double planetary gearset transmission so that the electric motors are the primary drive unit, with the ICE primarily used for battery replenishment and directly powering the front wheels in certain driving situations. Voilà! the Chevrolet Volt. - Which gets back to my original point about driveline packaging in the i8.

[Aye-eight]

Originally Posted by Efthreeoh

(1) Hub motors is far from a new idea and would really go against one of BMWs design axioms, which is to reduce unsprung weight. A 50+ horsepower electric motor in the rear hubs would absolutely kill the balance of the car with such a varied difference in unsprung weight between the front and rear suspensions. I remember in the late '80's reading about an upstart electric car company out of Denver IIRC that's design did exactly that had 4 50-HP electric motors one in each hub.

(2) Or perhaps, make a T-shaped battery pack out of uniquely deigned battery prism cells for designed-in cooling attributes, and set it low in the chassis in the center tunnel and under the rear seats. Then put a lightweight ICE under the hood with two compact electric motors for propulsion and charging, and all connected together using a complex double planetary gearset transmission so that the electric motors are the primary drive unit, with the ICE primarily used for battery replenishment and directly powering the front wheels in certain driving situations. Voilà! the Chevrolet Volt. - Which gets back to my original point about driveline packaging in the i8.

I didn't say hub motors were a new idea. In fact, all early (really early) EVs and hybrids, like the 1899 Lohner Porsche, had them. I was merely pointing out a potential approach to dealing with space issues. And maybe you can build some pretty lightweight ones if the rotor actually doubles as the wheel, rather than having a wheel bolted on.

Your option (2), if I'm reading it correctly, gives us a pure FWD vehicle, which is also un-BMW, which is maybe why it turned out to be a Chevy / Opel.

My point was simply that there are ways of fitting all those components into a proper sedan.

[Efthreeoh]

Originally Posted by Aye-eight

I didn't say hub motors were a new idea. In fact, all early (really early) EVs and hybrids, like the 1899 Lohner Porsche, had them. I was merely pointing out a potential approach to dealing with space issues. And maybe you can build some pretty lightweight ones if the rotor actually doubles as the wheel, rather than having a wheel bolted on.

Your option (2), if I'm reading it correctly, gives us a pure FWD vehicle, which is also un-BMW, which is maybe why it turned out to be a Chevy / Opel.

My point was simply that there are ways of fitting all those components into a proper sedan.

Well maybe FWD was un-BMW, but the new 1-series tells us different. Scott26 will be on here 10 years from now touting how the new 1.5L 3-cylinder K-Series 535i benefits from it's new FWD platform shared with the Toyota Camry....

Hub motors will never be light enought to not affect unsprung weight; there is the matter of physics.

[Aye-eight]

Originally Posted by Efthreeoh

Well maybe FWD was un-BMW, but the new 1-series tells us different. Scott26 will be on here 10 years from now touting how the new 1.5L 3-cylinder K-Series 535i benefits from it's new FWD platform shared with the Toyota Camry....

Hub motors will never be light enought to not affect unsprung weight; there is the matter of physics.

Alright, I think in the interest of everyone here, we should bring this discussion to a close.

But - can't help it - I do need to point out that, again, I didn't say hub motors would't affect unsprung weight. I said there may be ways to make them lighter. If unsprung weight was the non-plus-ultra of driving dynamics, all cars would be on magnesium wheels. In the end, everything is a trade-off - against cost and against competing usability factors. Like space. And sedans are the kings of trade-offs.

Finally, and I may get stoned for this, the reason why BMW even has a FWD platform is because of Mini. I draw my own conclusions on what that implies for the 1 series.

[Efthreeoh]

Originally Posted by Aye-eight

Alright, I think in the interest of everyone here, we should bring this discussion to a close.

But - can't help it - I do need to point out that, again, I didn't say hub motors would't affect unsprung weight. I said there may be ways to make them lighter. If unsprung weight was the non-plus-ultra of driving dynamics, all cars would be on magnesium wheels. In the end, everything is a trade-off - against cost and against competing usability factors. Like space. And sedans are the kings of trade-offs.

Finally, and I may get stoned for this, the reason why BMW even has a FWD platform is because of Mini. I draw my own conclusions on what that implies for the 1 series.

My point about hub motors not being a new idea is because as far as a packaging idea to get the motors out of the chassis and into the wheel is an obvious design attribute to add passenger and luggage space, and considering the advancement of EVs at this stage in the industry, it is apparent that that implementation of a hub-motor design has some significant detracting factors to it that outweigh (no pun intended) the benefit of packaging (i.e. it would already have been done). I would bet the detracting factors are unsprung weight, durability, and cost.

10 years ago BMW would have never been caught dead building a FWD-platform vehicle with a Roundel on it. I'm sure if either one of use took the time we could find several articles and interviews with BMW engineers that emphatically state the company's philosophy regarding the handling traits and benefits of a RWD architecture. Now that computer control handling dynamics have been able to artificially emulate RWD characteristics, BMW is finding reason to introduce a FWD BMW branded vehicle, which is the benefit of interior space. I know as recent as 5 years ago BMW published advertisements in all the major automotive magazines stating how it was the only manufacturer that did not platform-share between brands, because to do so induced compromises in the design of the vehicle. Apparently that philosophy has changed too.

Cheers

[MalibuBimmer]

Until about 12 years ago BMW engineers said they would never turbocharge their cars, having had a bad experience 40 years earlier with the 2002 turbo. Two years later everything was getting turbocharged.

[Aye-eight]

Originally Posted by Efthreeoh

My point about hub motors not being a new idea is because as far as a packaging idea to get the motors out of the chassis and into the wheel is an obvious design attribute to add passenger and luggage space, and considering the advancement of EVs at this stage in the industry, it is apparent that that implementation of a hub-motor design has some significant detracting factors to it that outweigh (no pun intended) the benefit of packaging (i.e. it would already have been done). I would bet the detracting factors are unsprung weight, durability, and cost.

Just something I came across on Wikipedia:

"The major disadvantage of wheel hub motors are that the weight of the electric motors would increase the unsprung weight, which adversely affects handling and ride (the wheels are more sluggish in responding to road conditions, especially fast motions over bumps, and transmit the bumps to the chassis instead of absorbing them). Most conventional electric motors include ferrous material composed of laminated electrical steel. This ferrous material contributes most of the weight of electric motors. To minimize this weight several recent wheel motor designs have minimized the electrical steel content of the motor by utilizing a coreless design with Litz wire coil windings to reduce eddy current losses. This significantly reduces wheel motor weight and therefore unsprung weight.[citation needed]

Another method used is to replace the cast iron friction brake assembly with a wheel motor assembly of similar weight. This results in no net gain in unsprung weight and a car capable of braking up to 1G.[20] A good example of this is the Michelin Active Wheel motor as fitted to the Heuliez Will that results in an unsprung weight of 35 kg on the front axle which compares favorably to a small car such as a Renault Clio that has 38 kg of unsprung weight on its front axle.[21]"

[Efthreeoh]

Originally Posted by Aye-eight

Just something I came across on Wikipedia:

"The major disadvantage of wheel hub motors are that the weight of the electric motors would increase the unsprung weight, which adversely affects handling and ride (the wheels are more sluggish in responding to road conditions, especially fast motions over bumps, and transmit the bumps to the chassis instead of absorbing them). Most conventional electric motors include ferrous material composed of laminated electrical steel. This ferrous material contributes most of the weight of electric motors. To minimize this weight several recent wheel motor designs have minimized the electrical steel content of the motor by utilizing a coreless design with Litz wire coil windings to reduce eddy current losses. This significantly reduces wheel motor weight and therefore unsprung weight.[citation needed]

Another method used is to replace the cast iron friction brake assembly with a wheel motor assembly of similar weight. This results in no net gain in unsprung weight and a car capable of braking up to 1G.[20] A good example of this is the Michelin Active Wheel motor as fitted to the Heuliez Will that results in an unsprung weight of 35 kg on the front axle which compares favorably to a small car such as a Renault Clio that has 38 kg of unsprung weight on its front axle.[21]"

Okay however, throw in cost and durability and see where the weight ends up.

[MakisI8]

Originally Posted by Efthreeoh

(1) Hub motors is far from a new idea and would really go against one of BMWs design axioms, which is to reduce unsprung weight. A 50+ horsepower electric motor in the rear hubs would absolutely kill the balance of the car with such a varied difference in unsprung weight between the front and rear suspensions. I remember in the late '80's reading about an upstart electric car company out of Denver IIRC that's design did exactly that had 4 50-HP electric motors one in each hub.

(2) Or perhaps, make a T-shaped battery pack out of uniquely deigned battery prism cells for designed-in cooling attributes, and set it low in the chassis in the center tunnel and under the rear seats. Then put a lightweight ICE under the hood with two compact electric motors for propulsion and charging, and all connected together using a complex double planetary gearset transmission so that the electric motors are the primary drive unit, with the ICE primarily used for battery replenishment and directly powering the front wheels in certain driving situations. Voilà! the Chevrolet Volt. - Which gets back to my original point about driveline packaging in the i8.

There is no need for the motors to be at the hub Its easy to install four motors inboard similar to old jaguars having the brake rotors and calipers inboard.
there are a lot of advantages on bringing them inboard as the wiring does not have to move with the suspension components.