Elon Musk revealed the Cybertruck last night, saying it looks like nothing else on the market. That’s true, but the Cybertruck shares several key features with an unlikely pickup — the first-generation Honda Ridgeline.
Both the Cybertruck and Honda Ridgeline are built differently from standard pickups. They employ a unibody design, much like what’s used in most passenger vehicles. Instead of a body sitting on a frame, the Cybertruck and Ridgeline are built around what is essentially a metal cage. A unibody truck makes sense for Tesla, which doesn’t want a large, bulky frame under the body. Tesla wants batteries under the vehicle and uses the body to protect them.
Because of the unibody pickup design, the vehicle has to employ a key design element to enable high-capacity towing: a sail pillar.
Most often, a vehicle’s towing capacity is limited by body design rather than engine strength. Towing places a lot of stress on the vehicle’s frame. Want to pull more? Make a beefier frame under the truck. But with the unibody Tesla Cybertruck, to increase the towing capacity, it had to use as big of a sail pillar as possible, explaining the unconventional design.
A vehicle naturally wants to twist. Think of wringing out a washcloth. In a body-on-frame design, the engine rests on a large frame, which absorbs a lot of the stresses. In a unibody design, vertical supports help, and are employed throughout, starting with an A pillar by the windshield and ending with a D pillar in the rear window of SUVs.
With a body-on-frame design, like what’s used in most pickups, the force from a trailer rests on the frame. Most of the energy is absorbed in the structure located under the body of the truck. The truck’s cab is decoupled from the bed, allowing the cab and bed to move relative to one another and better compensate for the stress on the frame.
In a unibody design, like in the Cybertruck, Ridgeline or most SUVs, the body is subjected to the same forces, but has to use the body to prevent twisting. The buttress-like sail pillar helps absorb the energy and prevent the truck from twisting.
Unibody SUVs have D pillars — the vertical supports at the rear of the vehicle — where pickups do not. This D pillar is needed to prevent the unibody from twisting and flexing when under load. But without the D pillar in a unibody pickup, a sail pillar connects the C pillar to the rear of the truck, achieving a similar result.
The first-generation Honda Ridgeline had a modest sail pillar, but Honda was able to ditch the feature for the second generation by reinforcing critical points throughout the unibody.
Honda described the redesign like this:
The rear frame structure of the 2017 Ridgeline is vitally important to the overall structural rigidity of the body, to collision safety performance and to the Ridgeline’s hauling and towing capability. Utilizing fully boxed frame members for the body sides and rear tailgate frame, the truss-style rear inner construction contributes to the new Ridgeline’s more conventional three-box design profile—allowing for the elimination of the buttress-style body structure in the forward portion of the upper bed on the previous model—while contributing to a 28-percent gain in torsional rigidity versus the previous model. Also, the U-shaped rear frame member serves as a highly rigid mounting structure for the rear tailgate, allowing for a highly precise tailgate fit.
The Chevrolet Avalanche also used a sail pillar to compensate for the lack of a D pillar. To make the Avalanche, Chevy took a full-size Suburban SUV and cut off the rear quarter.
It’s unclear if Tesla unveiled the final version of the Cybertruck. We still have significant questions. And if it’s not the final design, there’s a chance Tesla will be able to use some of Honda’s tricks to reduce the flying buttresses and produce a more conventional pickup design.