Controls that were once switches on a dashboard are now menus on a screen. The change was driven by manufacturing economics rather than by any evidence that screens are easier to use while driving.
Every physical control is a part with a supply chain
A button requires tooling, a supplier contract, a part number, inventory, wiring and a place in the assembly sequence.
Multiply that across dozens of switches and several trim levels and market variants, and the complexity is considerable.
A screen collapses all of it into one component, and the difference between a base model and a premium one becomes a software configuration rather than a different harness.
Wiring weight and packaging matter more than they appear to
The wiring harness in a modern vehicle is among its heaviest and most awkward components, and every discrete control adds to it.
Consolidating functions onto networked modules reduces the number of individual runs from the dashboard to the rest of the car.
That saves weight, frees packaging space and removes assembly steps, each of which has a measurable cost per vehicle.
Software allows change after the sale
A physical control is fixed for the life of the car. A screen interface can be revised through an update, which lets a manufacturer correct a poor layout or add a feature.
It also enables functions to be sold after delivery, since capability already built into the hardware can be enabled remotely.
That possibility has changed how manufacturers think about a vehicle's revenue, extending it beyond the initial transaction.
The interface cost falls on the driver
A physical switch can be found by touch, has a fixed position and gives feedback without a glance. A menu item requires visual attention to locate.
Research into driver distraction has consistently found that eyes-off-road time rises with tasks that require looking at a screen, which is why the trend has attracted regulatory interest.
Some safety rating programmes have begun considering the availability of physical controls for core functions in their assessments.
The pendulum is partly swinging back
Several manufacturers have reintroduced knobs for climate and volume while keeping screens for everything else.
Voice control and steering wheel controls are used to cover the same gap, since both allow adjustment without looking away.
The likely settlement is a split, where frequently used functions return to hardware and configuration remains on screen, because the cost argument and the usability argument apply to different sets of controls.