The battery-electric cabrio puts out a full 750 horsepower through its four permanent magnet synchronous electric motors – one for each wheel.What a Vision! Mercedes-Maybach Vision 6 Cabriolet is a Retro-Futuristic Show-StopperIt may also offer some hints as to ultra-luxury products to come.
by Paul A. Eisenstein on Aug.19, 2017

http://www.thedetroitbureau.com/2017/08/what-a-vision-mercedes-maybach-vision-6-cabriolet-is-a-retro-futuristic-show-stopper/

​A Change in Motor DesignThe 2017 Tesla Model 3 sedan uses a permanent magnet electric motor instead of the AC induction motors used in all Tesla products to date. | August 16, 2017 | Tesla​

https://www.edmunds.com/car-news/auto-industry/2017-tesla-model-3-has-unexpected-electric-motor-design.html​
​………………..

The big news is this: the Model 3 uses a permanent magnet (PM) electric motor instead of the AC induction motors used in all Tesla products to date.
It may sound like a nerdy difference, but this is a huge deal on many levels. Tesla’s entire identity is tied up with the AC induction motor, a type that Nikola Tesla himself patented in the late 1880s. Not only that, the Tesla logo is said to be a cross-section of one lobe of one of its own AC induction motors. Tesla is the only production electric carmaker with this type of motor, so it has historically bad-mouthed the PM motors used by everyone else. Tesla liked pointing out that PM motors tend to be less efficient when operated at higher speeds. Also, such motors are made from rare earth elements, which are mostly mined in China and are thus subject to trade politics. No wonder Tesla didn’t feel like revealing this nugget at the Model 3’s coming-out party, which was well-attended by Tesla fans who are invested in the Tesla story.
But none of this is bad news for consumers or deposit-holders waiting in line to buy a Model 3. In fact, it’s a good thing. For one, PM motors are more efficient, so long as you’re not intent on building a hyperperformance machine. This makes them a better choice for daily-driven commuter vehicles. Not to oversimplify it too much, but AC induction motors have to use some of the electricity stored in the car’s battery to generate the necessary magnetism within the motor. Permanent magnet motors have no need for this because they are made using, as the name suggests, permanently magnetic materials.
This change has many cascading benefits, especially if you are trying to build a smaller, less-expensive electric car. A more efficient electric motor means you can use a smaller battery to achieve a given range, which not only lowers the price, but also reduces the battery’s weight and footprint. A smaller and lighter battery in turn allows for a smaller and lighter car, which increases efficiency and range and reduces the need for a big motor even more. It’s a self-reinforcing change that makes the Model 3 possible, as well as affordable.

https://learnbonds.com/135002/tesla-inc-tsla-tesla-model-3-image-breaker/
​
There’s an argument to be had over what type of motor should go in an EV. When Tesla was designing the Roadster and the Model S it had that argument. The firm’s original mavens, before Elon Musk became CEO, decided an AC induction motor was preferable because of the higher performance.In the early cars from Fremont, performance was key. With the Tesla Model 3, however, efficiency appears to have the upper hand.
Back in 2007 EV giant Wally Rippel wrote about the Tesla, Inc. (NASDAQ:TSLA) decision to choose the AC motor. The blog post is relatively long and technical, but the basic conclusion is easy to understand. AC motors have better performance and they likely have a cost advantage.
There are also questions about efficiency. A PM car is intrinsically more efficient because the motor needs less power to run. It also produces less heat, adding to the efficiency.
The choice of original Tesla founders Martin Eberhard and Marc Tarpenning to use the AC induction motors was one of the things that set it apart. Now Elon Musk, who took an interest in the firm in its first funding round, wants to change that direction.
Why did Tesla change its motors?

​Why did Tesla change its motors?

We know that the cost of permanent magnet motors has been on the minds of Fremont boffins in recent months. An April interview with Konstantinos Laskaris, head of motor design, undertaken by ChargedEVs.com, may have given the game away early.

When asked about motor cost he said, unprompted, “When we’re talking about permanent-magnet motors, the magnet price in the past has fluctuated so much that maybe this is not very representative of a general discussion about motor cost.”
At the time, as far as anyone could see, the firm didn’t put that kind of motor in anything. Despite that, Laskaris continued, saying that costs of motors were still going lower because of optimization. The entire piece is full of interesting ideas about the future of Tesla motor design. Given that it appears to have pointed to this revelation, there may be more secrets hidden in his answers.
What we can take away from the discussion is informative, however. Tesla has likely made the permanent magnet style motors cheap enough to be worth using. When it comes to the Tesla Model 3, after all, cost and margins are the most important part of the equation.