One of Apple's suppliers is working on a pressure-sensitive windshield that's a lot like the iPhone 6S

Apple supplier Synaptics is developing a touchscreen windshield for cars that detects how hard a user is pressing on it, a feature that is very similar to 3D Touch, a banner feature on late-model Macbooks and the latest iPhones.

Synaptics is working with Valeo, a major automotive supplier that recently demoed a self-driving autopilot feature. It has also developed several concept interfaces for users to interact with autonomous vehicles.

"This human interface innovation allows drivers and passengers to more safely control common and emerging cabin applications with the touch of a finger, multiple fingers, and variable force of one or more fingers on a touchscreen," said Synaptics.

Although it's unclear whether Synaptics provides the parts that make 3D Touch possible on Apple products, it is one of the company's top 200 suppliers. Synaptics manufactures display driver parts that Apple uses for the iPhone 6S, according to a teardown by Chipworks.

Even if Synaptics isn't directly responsible for supplying the underlying technology behind 3D Touch, the company's announcement of its touchscreen windshield that can detect force shows that this style of interaction is becoming more and more popular.

On the iPhone, 3D Touch works like a "right click": users simply press down with extra force on the phone's screen to find additional user options. Synaptics calls its version of the technology ClearForce, and it sells it to Android smartphone makers that compete with Apple. Synaptics works with other tech companies including Microsoft, Google, and Samsung.

Apple is supposedly developing a car, a rumor that Tesla CEO Elon Musk has called an "open secret." Given Apple's corporate emphasis on user experience, it would make sense that one of the company's primary focuses for "Project Titan" would be an Apple-style user interface.

In August, the Washington Post reported that Apple is developing an augmented-reality windshield with a display as large as 50 inches, although analysts cited by the report indicated that the screen could be "gesture-controlled," which would make a pressure-sensitive touchscreen less critical.

Apple reportedly has a team of hundreds working on augmented reality applications, and the Financial Times reports that Apple's recent hires in the worlds of imaging and augmented reality may be useful for its car project.

Synaptics has yet to announce a firm timeline as to when it will roll out its touchscreen windshields and technology.