Tesla Cybertruck's Closed Tonneau Adds 25 Miles of Range at 75 MPH

• The 2024 Tesla Cybertruck is more aerodynamic than it looks, and it's roll-top tonneau cover plays an essential role.

• We tested the Cybertruck with the top open and closed; the latter position provided a 10 percent improvement in consumption during our 75-mph steady state test.

• Our tests show the Cybertruck's real-world range drops from 250 to 225 miles with the top open; driven at 65 mph with the top closed, we predict a range of 295 miles.

The Tesla Cybertruck is more friendly to the air than you might imagine. The front end was always going to be a challenge, but the prototype’s flat nose was changed to a subtly curved front panel that helps the air bend around the forward flanks. What’s more, the front flares have been carefully shaped to create a small, deliberate vortex that helps to further encourage the flow to bend smoothly around those abnormally sharp front corners. The prominent wiper acts like a fence that directs air over the top instead of allowing it to swirl down onto the driver’s window, so wind noise isn’t as turbulent as you might guess—for the driver, at least. Underneath, the Cybertruck's belly is much smoother than any ladder-framed truck could ever hope to be, with minimal openings and fairings to smooth the flow over the suspension’s lower control arms.

Arguably the most surprising aspect about the Cybertruck's aerodynamics is how naturally well-suited the angular-looking aft end actually is. The rearmost flanks taper gently like some kind of raindrop, which is the most naturally aerodynamic shape. Thing is, the abrupt truncation at the tailgate is actually quite good aero-wise. Wunibald Kamm (of Kammback fame) once demonstrated that such an abrupt cut-off would essentially trick the majority of the air flowing over such a body into continuing on a laminar path, thereby reducing drag more than a smoothly rounded design might achieve.

Of course, the Cybertruck's roll-top tonneau cover is essential to all of this, so we conducted 75-mph steady state tests with the tonneau closed, open, and with the tonneau and tailgate open together to presumably create an exit for the air “captured” by the exposed bed. We also wondered about the effect of the wheel caps, so we repeated our tonneau-closed runs with them off.