Sloped roof and drag

[Daniel_R]

Hi,

Is the aggressively sloped roof really that important to reduce drag or is it more a design choice?

I would have preferred less slope and more cargo space.

Daniel

 

[Woosie]

Yes, the slopes roof contributes significantly to the 0.23 drag coefficient I recall Elon Musk saying during the unveiling.

This affects range in a big way.

 

[ac_power]

Design is probably a big part of it, but what they're doing from aerodynamic perspective, is tapering down the tail in laminar manner to shrink down turbulent zone. Laminar flow has lower surface friction, but can create much lower pressure on negative slope than turbulent one, thus generating more drag (and lift actually). So it's a good question how much they're winning here. Golf- or Prius-V-sort-of design may be not much worse from aerodynamic perspective, but I should admit that BMW X6 lines look more appealing.

 

[GenSao]

Yes. The Coefficient of Drag of 0.23 for the Tesla Model Y is very low. Going with a crossover shape would likely increase the Coefficient of Drag. To compensate, Tesla could add batteries to increase weight and cost or keep the reduced range.

For reference, the Toyota Prius (3rd Generation) has a Coefficient of Drag of 0.25 with a similar tapered roof. The Toyota Prius V (3rd Generation variant) has a Coefficient of Drag of 0.29 with a crossover roof. Subsequently, the average fuel economy goes down from 48 MPG to 41 MPG. Roughly a 15% loss.

Many of the EV competition for the Model Y have a Coefficient of Drag between 0.28 to 0.30. Nissan Leaf+ = 0.28, Hyundai Kona = 0.29, Jaguar I-Pace = 0.29, Kia Nero = 0.30, Audi etron = 0.30

 

[Robocheme]

Yes. The Coefficient of Drag of 0.23 for the Tesla Model Y is very low. Going with a crossover shape would likely increase the Coefficient of Drag. To compensate, Tesla could add batteries to increase weight and cost or keep the reduced range.

For reference, the Toyota Prius (3rd Generation) has a Coefficient of Drag of 0.25 with a similar tapered roof. The Toyota Prius V (3rd Generation variant) has a Coefficient of Drag of 0.29 with a crossover roof. Subsequently, the average fuel economy goes down from 48 MPG to 41 MPG. Roughly a 15% loss.

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Many of the EV competition for the Model Y have a Coefficient of Drag between 0.28 to 0.30. Nissan Leaf+ = 0.28, Hyundai Kona = 0.29, Jaguar I-Pace = 0.29, Kia Nero = 0.30, Audi etron = 0.30

Excellent info. I always wondered about how much the tapered roof gets you. It seems like the Y will look a lot like the X4.