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This is a pretty funny thing to be concerned about. Almost none of us will have these cars by the time 100k miles rolls around, let alone when these motors fail. It's a non-issue. If the motors fail, it will be because of some mechanical defect, not these brushes. Also lots and lots of Tesla motors have failed over the years. The Model X has some suspension bits that are essentially wear items, they fail so often. Meanwhile, my FRS's valve springs had to be replaced under a recall, and my Neon had a head gasket failure at 45k miles.
Like @Cable Guy, 100K miles is not by a long stretch the end one of my cars' life. My older car is 20 years old and has 167,000 miles (269 000km), I just changed the transmission oil, filters and spark plugs so I'm confident I'll get to at least 186,000 miles (300 000km). The i4 is the last new car I'll ever buy, so I fully intend to drive it to the ground - I'm already planning to drive it as is for 12-15 years, then swap out the battery pack and go on for another 12-15 years...
 

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I sit corrected. I haven't ever, in my entire life, taken a car from new to 100k. We have a Subaru with over 80k, but it's our beater and will be soon given to our daughter once I fix the brakes. Once I get time to fix the brakes.
 

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i4 M50, 19" Wheels
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My car (E class Merc) is 14 years old and done 135,000 miles. Been incredibly reliable. I too plan to keep the i4 for at least 10 (probably 15) years, my only concern is the battery but my mileage now is quite low, 6-7,000 miles a year, so I'm hoping to get a long life out of the car.

I have a very good car ATM and I've never seen the point in the expense of a new car when the improvements are only incremental. I'm also not into getting a new car 'because I fancy a change'. When I briefly looked at EVs a few years ago I was underwhelmed and a bit scared of making the transition to EV. I was planning to keep the Merc longer (until something major broke) and then I saw a Polestar 2 on Top Gear. First time I saw a car on TV and thought "I'm excited about that, must investigate further". (OK, so I like the supercars too but that is as realistic as me watching "No Time to Die" and thinking I would like to be James Bond.) I got quite far along deciding to get the Polestar but then switched to the i4.

Now my wife won't let me watch Top Gear any more 😭
 

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2022 e40 Sport
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Of course BMW would pick the motor design that will require expensive maintenance after the warranty ends.
Why would you think that? The only major wearable part in the motor are the brushes which are designed into a replaceable unit. Are you also worried about the bearings that are in everything that rotates? There was an article about a Tesla owner with a million miles. Battery was replaced once, motor eight times.
 

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‘22 i4 eDrive40 🍉
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Of course BMW would pick the motor design that will require expensive maintenance after the warranty ends.
Anyone with 19+" wheels is going to spend far more on tires during the life of the car.

Take another look at the photo above, realize that the "brushes" are basically made like brake pads, think about how long brake pads would last if they were that thick, and realize that these are under the lightest pressure and well-lubricated.

They're going to last rather a long while, it seems.

And if you're still convinced that this is some kind of terrible design, go look at what a bearing replacement will cost in a competing PMM design. Those aren't "lifetime" parts either, technically.
 

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Why would you think that? The only major wearable part in the motor are the brushes which are designed into a replaceable unit. Are you also worried about the bearings that are in everything that rotates? There was an article about a Tesla owner with a million miles. Battery was replaced once, motor eight times.
Because they have a dealership network to maintain, whose profits come mainly from maintenence and repairs. What happens to them if they start selling cars that don't need things like motor brush replacements? It's actually the perfect part for them because they can design brushes that will burn out whenever they need them to for maximum income. Planned obsolence. Brushes wearing out before the warranty ends? A slight redesign will fix that. Brushes lasting too long and dealerships struggling for cash? Tweak them again. Can't do that with a rare earth magnet motor. They need something that is the equivalent of the timing belts on an ICE car, that they can call "regular wear" and charge you thousands for periodically.
 

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Anyone with 19+" wheels is going to spend far more on tires during the life of the car.

Take another look at the photo above, realize that the "brushes" are basically made like brake pads, think about how long brake pads would last if they were that thick, and realize that these are under the lightest pressure and well-lubricated.

They're going to last rather a long while, it seems.

And if you're still convinced that this is some kind of terrible design, go look at what a bearing replacement will cost in a competing PMM design. Those aren't "lifetime" parts either, technically.
Well yes, you'll need to replace the tires on any car. But with brush motors you're going to have to replace the tires AND the brushes. Its an additional point of cost and maintenance. Lubrication wears out. The brushes will wear down. The fact that they're boasting how well the particles will be contained affirms that they'll be degrading.
 

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Well yes, you'll need to replace the tires on any car. But with brush motors you're going to have to replace the tires AND the brushes. Its an additional point of cost and maintenance. Lubrication wears out. The brushes will wear down. The fact that they're boasting how well the particles will be contained affirms that they'll be degrading.
The rest of my post, after the line about tires, addresses this. Your dismissive reply about replacing the tires on any car ignores the fact that a large number of buyers are already buying something because they want it, and not because it was the cost-effective alternative to a Prius Prime.

With regard to the motor, BMW has only a decade of experience making electric cars, but that's rather a lot overall by comparison. I suspect they know what they're doing. And again, if you read my post, and you look at the design, you'll see that there is a HUGE amount of "brush" material available.

The fact that they're boasting how well the particles will be contained affirms that they'll be degrading.
Wear and degradation are not the same thing. There is absolutely no evidence that the quality of the brush performance will be reduced with use, time, or wear.
 

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The rest of my post, after the line about tires, addresses this. Your dismissive reply about replacing the tires on any car ignores the fact that a large number of buyers are already buying something because they want it, and not because it was the cost-effective alternative to a Prius Prime.

With regard to the motor, BMW has only a decade of experience making electric cars, but that's rather a lot overall by comparison. I suspect they know what they're doing. And again, if you read my post, and you look at the design, you'll see that there is a HUGE amount of "brush" material available.


Wear and degradation are not the same thing. There is absolutely no evidence that the quality of the brush performance will be reduced with use, time, or wear.
Your reasoning seems to be - well people want this car so it's fine that BMW chose a path that will lead to more expensive maintenance. Just because it's not a prius doesn't mean people want to go to the dealership and fork over a few thousand dollars every few years. Especially when the marketing for EVs is "less maintenance!"

Renault uses brush motors and owners report noise as they wear down. Renault says they're still working fine and the warranty doesn't cover noise.

Wear vs degredation? Semantics. We're talking about an additional part that has to be replaced over time. Like a timing belt. If ICE makers had the option of using timing belts that never need replacing or timing belts that DO need replacing, would you defend the choice to use the ones that DO need replacing? We know the dealerships sure would.
 

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Your reasoning seems to be - well people want this car so it's fine that BMW chose a path that will lead to more expensive maintenance. Just because it's not a prius doesn't mean people want to go to the dealership and fork over a few thousand dollars every few years. Especially when the marketing for EVs is "less maintenance!"

Renault uses brush motors and owners report noise as they wear down. Renault says they're still working fine and the warranty doesn't cover noise.

Wear vs degredation? Semantics. We're talking about an additional part that has to be replaced over time. Like a timing belt. If ICE makers had the option of using timing belts that never need replacing or timing belts that DO need replacing, would you defend the choice to use the ones that DO need replacing? We know the dealerships sure would.
BMW chose a path that does not require permanent magnets in the motors and as such no rare earth materials.

Since the motor has to be electrically excited, brushes are required. By not having permanent magnets BMW doesn't have some issues related to supply chain of those minerals. It also allows BMW to freewheel the motor in coasting with only parasitic drag coming from rotation and friction. Does not have to worry about induced fields, etc

BMW also hasn't used a timing belt since the failed ETA engine. The figured that a chain that has very little stretch, more noise, no maintenance is much better.

I wouldn't worry about brushes and replacement.
Brushes can't be more than a couple hundred and are.probably easy to change once you pull the end cover off.

It took about 20 minutes to swap out the brushes on my alternator while it was still in the car (E90 335i).

Waiting for my M50......
 

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Yea, I saw another YouTube review, it says that BMW Electric Engine is not using Permanent magnets.... and it would last only 180k miles?

How much will cost us to replace one or two electric motor after few years warranty and 80k miles warranty? LOL
 

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2023 i4 m50 Portimao/Oyster
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Yea, I saw another YouTube review, it says that BMW Electric Engine is not using Permanent magnets.... and it would last only 180k miles?

How much will cost us to replace one or two electric motor after few years warranty and 80k miles warranty? LOL
Whoever claimed that has no idea what they are talking about and is very likely a Tesla fanboi. The statement is correct that they don't use permanent magnets like Teslas and most other EVs (this is a very good thing!), but the durability of these motors has not been tested and cannot be claimed like this.

See Motor maintenance for earlier conversations on this and an article about the motors.
 
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How about LABOUR???
Probably a few hours is my guess. You can replace the brushes on an alternator while it's in the car.

My E90 needed new brushes on the alternator after 140K miles. Took about an hour with it in the car.

I suspect the motors, at least that portion will be accessible since they know it's a wear item.

Waiting for my M50......
 
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