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Interesting point. This should actually be an advantage for Tesla as the engineering and manufacturing costs would be much lower to produce front, rear and all

Interesting point. This should actually be an advantage for Tesla as the engineering and manufacturing costs would be much lower to produce front, rear and all wheel drive options than a traditional ICE car. I'm guessing they're hoping people buy the dual motor option for this scenario though.

fingerlocks 8y ago
Why would the costs be lower? Honest question. On an ICE vehicle the only difference between rear and all wheel drive is a differential and a drive shaft. Maybe I don’t know enough about electric vehicles, but “dual motor” sounds a lot more expensive.
- londons_explore 8y ago
  Big electric motors are actually pretty cheap. They've existed in industry for over a century, and their manufacture is entirely automated. The raw materials cost of two motors each with half the power matches that of one motor. The motor controllers are probably the more expensive part, although most of the cost there is engineering design cost (much of industry doesn't use fancy motor controllers needed for a car, and cars use high power MOSFETs which are rapidly evolving tech). Tesla designing them in house will eliminate much of the cost over enough volume.
- pedrocr 8y ago
  > On an ICE vehicle the only difference between rear and all wheel drive is a differential and a drive shaft. You need three differentials for AWD as you first need to split the power front/back and then right/left in each axle. That's two more differentials than in just RWD or FWD. You also need to package all that together with a gearbox. That's why many manufacturers don't even offer an AWD option, and having both FWD and RWD versions of a car is very rare if it happens at all. Meanwhile Tesla already builds all their cars to have two independent motors front/back each with their differential. They could very easily build a FWD car right now just by omitting the rear assembly. The cars are apparently even already designed to work with just the front motor for reliability so even the software update would be simple. And building AWD cars by having two electric motors is almost surely not more expensive than the ICE way. Electric motors are much simpler than combustion ones and you eliminate all the mechanical parts needed to split the power between the axles. Control also becomes much better as the software gets to adjust power independently to both axles.
  - dsfyu404ed 8y ago
    >And building AWD cars by having two electric motors is almost surely not more expensive than the ICE way. You need a differential for each driven axle. The expense of the extra motor and motor controller vs the expense of the transfer case (or FWD based equivalent), and drive shaft (not really all that expensive) is probably close to a wash or slightly in favor of the ICE vehicle. I don't think you understand how cheap and commoditized drive-train parts are. Like really, these assemblies are cheap and almost go together like legos (from an OEM perspective). It's not like you burn tons of engineering hours making a FWD or RWD vehicle into AWD so long as whatever floor pan you're working with was designed to be AWD compatible.
    - pedrocr 8y ago
      Thinking about it some more, maybe in a mass produced ICE AWD can indeed be a cheaper add-on. Something like a Subaru that does AWD for all cars. I was thinking more of the direct Tesla competitors that tend to charge quite a bit for AWD as an extra. But it's hard to compare from the outside as adding AWD to a car is often associated with different trim levels too. Someone like Sandy Munro that does detailed costing would be able to answer this definitively for a few models. But it will most likely depend on the actual implementation to see what ends up cheaper. According to Munro Tesla has a big advantage in the cost, weight and performance of the motors right now compared to other EVs so that might be enough to tip the scale. I'd love actual data though.
sliken 8y ago
Well there's a few problems with that. First of all FWD saves money, complexity, and weight on an ICE car because you avoid a long drive shaft, and you can mount the engine transversely which is more compact. You also get more interior room in the car since there's no hump for the drive shaft. With an electric car you don't save anything with RWD vs FWD, you end up with poorer steering, poorer acceleration, and worse hill climbing, especially if it's snowy or icy. Nor is it cheaper to produce. As a result even electric cars intended for city use like the BMW i3 and Renault have RWD. On the model 3 the rear motor is larger and a permanent magnet motor (which is more efficient) and the front motor is an induction motor. So a FWD would have less power than the RWD, and it would also have less range than the RWD. Not sure Tesla would want to try to sell a car slower (because FWD), slower (because of less HP), and with less range (because of efficiency) without it being cheaper to produce.... just to have a FWD.

fingerlocks 8y ago

Why would the costs be lower? Honest question. On an ICE vehicle the only difference between rear and all wheel drive is a differential and a drive shaft. Maybe I don’t know enough about electric vehicles, but “dual motor” sounds a lot more expensive.

londons_explore 8y ago
Big electric motors are actually pretty cheap. They've existed in industry for over a century, and their manufacture is entirely automated. The raw materials cost of two motors each with half the power matches that of one motor. The motor controllers are probably the more expensive part, although most of the cost there is engineering design cost (much of industry doesn't use fancy motor controllers needed for a car, and cars use high power MOSFETs which are rapidly evolving tech). Tesla designing them in house will eliminate much of the cost over enough volume.
pedrocr 8y ago
> On an ICE vehicle the only difference between rear and all wheel drive is a differential and a drive shaft. You need three differentials for AWD as you first need to split the power front/back and then right/left in each axle. That's two more differentials than in just RWD or FWD. You also need to package all that together with a gearbox. That's why many manufacturers don't even offer an AWD option, and having both FWD and RWD versions of a car is very rare if it happens at all. Meanwhile Tesla already builds all their cars to have two independent motors front/back each with their differential. They could very easily build a FWD car right now just by omitting the rear assembly. The cars are apparently even already designed to work with just the front motor for reliability so even the software update would be simple. And building AWD cars by having two electric motors is almost surely not more expensive than the ICE way. Electric motors are much simpler than combustion ones and you eliminate all the mechanical parts needed to split the power between the axles. Control also becomes much better as the software gets to adjust power independently to both axles.
- dsfyu404ed 8y ago
  >And building AWD cars by having two electric motors is almost surely not more expensive than the ICE way. You need a differential for each driven axle. The expense of the extra motor and motor controller vs the expense of the transfer case (or FWD based equivalent), and drive shaft (not really all that expensive) is probably close to a wash or slightly in favor of the ICE vehicle. I don't think you understand how cheap and commoditized drive-train parts are. Like really, these assemblies are cheap and almost go together like legos (from an OEM perspective). It's not like you burn tons of engineering hours making a FWD or RWD vehicle into AWD so long as whatever floor pan you're working with was designed to be AWD compatible.
  - pedrocr 8y ago
    Thinking about it some more, maybe in a mass produced ICE AWD can indeed be a cheaper add-on. Something like a Subaru that does AWD for all cars. I was thinking more of the direct Tesla competitors that tend to charge quite a bit for AWD as an extra. But it's hard to compare from the outside as adding AWD to a car is often associated with different trim levels too. Someone like Sandy Munro that does detailed costing would be able to answer this definitively for a few models. But it will most likely depend on the actual implementation to see what ends up cheaper. According to Munro Tesla has a big advantage in the cost, weight and performance of the motors right now compared to other EVs so that might be enough to tip the scale. I'd love actual data though.

sliken 8y ago

Well there's a few problems with that. First of all FWD saves money, complexity, and weight on an ICE car because you avoid a long drive shaft, and you can mount the engine transversely which is more compact. You also get more interior room in the car since there's no hump for the drive shaft. With an electric car you don't save anything with RWD vs FWD, you end up with poorer steering, poorer acceleration, and worse hill climbing, especially if it's snowy or icy. Nor is it cheaper to produce. As a result even electric cars intended for city use like the BMW i3 and Renault have RWD. On the model 3 the rear motor is larger and a permanent magnet motor (which is more efficient) and the front motor is an induction motor. So a FWD would have less power than the RWD, and it would also have less range than the RWD. Not sure Tesla would want to try to sell a car slower (because FWD), slower (because of less HP), and with less range (because of efficiency) without it being cheaper to produce.... just to have a FWD.