My wife and I are considering a Tesla. A major part of my thinking is that EVs will far outlast their ICE equivalents, redefining the life expectancy of a car with fewer headaches along the way and with significant cost-savings over decades of ownership, even for those who buy the highest end models. I've put together a spreadsheet/model that I believe validates this; more on that later.
Maintenance and gas savings are easy to calculate; I would like to address some less-talked-about points relating to drivetrain and structural lifespan. Please assume for the sake of this discussion that the goal is to drive the Tesla for as long economically beneficial, thereby minimizing the "cost per mile driven" over the lifetime of the car. So the question is: just how far can a Tesla be driven at a fixed cost, and can it go even farther with small enough variable costs that the cost per mile driven continues to go down?
I began this process by thinking about what stops an ICE from going. I think there are two main culprits:
1) The frame rots, and thus it is either unsafe or it requires regular welding to keep it safe.
2) Expensive repairs combined with the possibility of more expensive repairs makes people hesitant to do the needed work.
On point #1, the Tesla S has an aluminum frame rather than a steel one. Thus it isn't susceptible to rusting and should last indefinitely, subject to accident avoidance.
Point #2 is the more common problem. It's not that you may need to spend $2,000 on a new transmission at 200k miles that causes you to give up on your car; it's that after you spend that $200k, you might need to have the timing belt done, or the engine rebuilt, or the water pump replaced -- all of which are looming and you don't know exactly when disaster will strike. And so there is a fear that you are throwing good money after bad because of the risk of the unknown, so you sell it or donate it and move on for a newer vehicle that is a safer bet.
Tesla seems to address, this problem, too. There are two expensive repairs that I can foresee looming over an old Tesla -- the motor and the battery. A worst case is that both fail, and so it should be a bit less nerve-racking to replace them on an older vehicle because unlike an ICE, once they are replaced, you have an entirely new drive system.
Assuming degradation is acceptable, and based on Tesla's once-marketed 10-year battery replacement cost, I think it is a reasonable bet that in 15-20 years, you'll be able to buy an 85kW replacement battery for ~$10,000. It is possible the battery will last longer than 20 years, or shorter, but that seems like a reasonable lifetime before catastrophic failure if the degradation is acceptable.
The motor is more difficult to judge. Obviously any moving part has a lifespan, but a brushless motor is so simple and efficient that I can't personally imagine what that lifespan is. I can't foresee anything that would cause it to fail at its core. Even with Tesla's early drivetrain woes, the problems were mainly in the angle of the gear shaft, not in the core itself. When discussing the 8-year unlimited mile warranty, Elon once said that Tesla has a car in a lab with 500,000 miles on it, making the point that he doesn't think anyone will be able to "kill" the battery or drivetrain assembly.
I made a spreadsheet, which I link to below. It compares several 4WD cars to a Tesla S to calculate the cost of each car per mile driven. As mentioned earlier, I assume a new $10,000 battery at 200k-mile intervals. For the motors, I assume it will need $4,000 of gearing work at 200k-mile intervals. If I put in Elon's 500,000 mile lifetime figure, the Tesla blows everything away. If I use 300,000 -- more than ICEs but much less than Elon's number -- the Tesla is still cheaper per mile driven than all but the Subarus -- and those costs include MA's very high electricity costs.
But can any car really last for 300k miles, let alone 500k+ miles? All of my thinking and calculations convince me it can. But because EVs are so new and so much is merely lab-proven rather than road-proven, I want to do everything I can to question this belief before making a purchase decision.
Questions that would help me are:
Do you see any flaws in my logic?
Are there factors that limit how long a car can realistically run for that I've failed to address?
Are there major expenses I've failed to account for?
Here is the cost per mile driven as calculated by my spreadsheet:
Tesla S 85: $0.48
Tesla S 85 Performance Plus: $0.51
Subaru XV Crosstek: $0.39
Subaru Outback 2.5i Limited: $0.43
Audi Q3 Prestige: $0.58
Toyota Highlander Hybrid: $0.57
Honda Odyssey EX-L: $0.48
Mercedes GLK-350: $0.49
Here is my spreadsheet: Google Sheets - create and edit spreadsheets online, for free.
Maintenance and gas savings are easy to calculate; I would like to address some less-talked-about points relating to drivetrain and structural lifespan. Please assume for the sake of this discussion that the goal is to drive the Tesla for as long economically beneficial, thereby minimizing the "cost per mile driven" over the lifetime of the car. So the question is: just how far can a Tesla be driven at a fixed cost, and can it go even farther with small enough variable costs that the cost per mile driven continues to go down?
I began this process by thinking about what stops an ICE from going. I think there are two main culprits:
1) The frame rots, and thus it is either unsafe or it requires regular welding to keep it safe.
2) Expensive repairs combined with the possibility of more expensive repairs makes people hesitant to do the needed work.
On point #1, the Tesla S has an aluminum frame rather than a steel one. Thus it isn't susceptible to rusting and should last indefinitely, subject to accident avoidance.
Point #2 is the more common problem. It's not that you may need to spend $2,000 on a new transmission at 200k miles that causes you to give up on your car; it's that after you spend that $200k, you might need to have the timing belt done, or the engine rebuilt, or the water pump replaced -- all of which are looming and you don't know exactly when disaster will strike. And so there is a fear that you are throwing good money after bad because of the risk of the unknown, so you sell it or donate it and move on for a newer vehicle that is a safer bet.
Tesla seems to address, this problem, too. There are two expensive repairs that I can foresee looming over an old Tesla -- the motor and the battery. A worst case is that both fail, and so it should be a bit less nerve-racking to replace them on an older vehicle because unlike an ICE, once they are replaced, you have an entirely new drive system.
Assuming degradation is acceptable, and based on Tesla's once-marketed 10-year battery replacement cost, I think it is a reasonable bet that in 15-20 years, you'll be able to buy an 85kW replacement battery for ~$10,000. It is possible the battery will last longer than 20 years, or shorter, but that seems like a reasonable lifetime before catastrophic failure if the degradation is acceptable.
The motor is more difficult to judge. Obviously any moving part has a lifespan, but a brushless motor is so simple and efficient that I can't personally imagine what that lifespan is. I can't foresee anything that would cause it to fail at its core. Even with Tesla's early drivetrain woes, the problems were mainly in the angle of the gear shaft, not in the core itself. When discussing the 8-year unlimited mile warranty, Elon once said that Tesla has a car in a lab with 500,000 miles on it, making the point that he doesn't think anyone will be able to "kill" the battery or drivetrain assembly.
I made a spreadsheet, which I link to below. It compares several 4WD cars to a Tesla S to calculate the cost of each car per mile driven. As mentioned earlier, I assume a new $10,000 battery at 200k-mile intervals. For the motors, I assume it will need $4,000 of gearing work at 200k-mile intervals. If I put in Elon's 500,000 mile lifetime figure, the Tesla blows everything away. If I use 300,000 -- more than ICEs but much less than Elon's number -- the Tesla is still cheaper per mile driven than all but the Subarus -- and those costs include MA's very high electricity costs.
But can any car really last for 300k miles, let alone 500k+ miles? All of my thinking and calculations convince me it can. But because EVs are so new and so much is merely lab-proven rather than road-proven, I want to do everything I can to question this belief before making a purchase decision.
Questions that would help me are:
Do you see any flaws in my logic?
Are there factors that limit how long a car can realistically run for that I've failed to address?
Are there major expenses I've failed to account for?
Here is the cost per mile driven as calculated by my spreadsheet:
Tesla S 85: $0.48
Tesla S 85 Performance Plus: $0.51
Subaru XV Crosstek: $0.39
Subaru Outback 2.5i Limited: $0.43
Audi Q3 Prestige: $0.58
Toyota Highlander Hybrid: $0.57
Honda Odyssey EX-L: $0.48
Mercedes GLK-350: $0.49
Here is my spreadsheet: Google Sheets - create and edit spreadsheets online, for free.
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