A Tesla Model 3 owner figured out that his electric car is much more efficient with a roof-rack box gets if he flips the box around.

Electrek, By Fred Lambert

© Electrek | Tesla Model 3 with roof-rack box gets much better range if you flip box around

With Model 3’s glass roof, there wasn’t a clear way to safely install a roof rack to transport things like bikes or skis.

That said, we knew it was possible since Tesla designed one for the Model S with a glass roof, and a Model 3 prototype was spotted with a roof rack in 2017.

More than a year later, Tesla finally launched the roof rack as a $450 aftermarket product on its shop website. The product has been so popular that it has sold out on several occasions.

Now a Tesla Model 3 owner in Sweden has made a simple discovery with his roof-rack box that increases the efficiency quite a bit.

Peter Fritzson, a Tesla Sweden Club member, decided to turn his roof box around at the suggestion of his neighbour who is an aerodynamic performance expert:
He conducted some tests to see how it impacts efficiency, and the results are surprising.

Fritzson says that the roof rack alone impacts efficiency by about 3.6%.

When the roof box is installed the way it is recommended by the manufacturer (right image above), it reduces the range by about 16%.

The Model 3 owner says that his car gets the same range as if the roof rack is installed without the box if the box is installed with the larger side forward.

The shape is definitely more aerodynamic. You can think of the wings of an aeroplane or a raindrop. So why are roof-box makers not recommending that they are installed like that?

Aerodynamics researcher R. Jason Hearst at NTNU explains to Norway’s TU:
Well, they definitely know about this. There are several reasons. One of them is the aesthetics; people buy products that look the way they expect. After all, the car has the pointed part in front, and the box should match the car.
Other than that, Hearst also explained that the aerodynamic performance of the box can affect different cars in different ways and increase turbulence and noise.

He wouldn’t recommend that everyone turn their roof box around even if it improves efficiency.

This article was originally published by Electrek.
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