Usability in a moving vehicle
Electric Vehicles like the Tesla Model 3 are the latest web devices you could design your apps for. The accessibility context of a moving vehicle is very different from the accessibility context of desktop sitting on a table. There are both safety and accessibility concerns when designing an application for use/interaction during a drive.
Here are a few things to keep in mind while designing for users behind the wheel:
1. Attention Span
Almost 100% of their attention is towards driving safely and adapting to ever changing road conditions. Whatever your app does, it must be quick, direct, simple, and easy to quit.
2. Main Functionality
Keep your app's main functionality and the exit buttons above-the-fold at all times, and preferably near the upper edge of the bezel or the center of the screen.
3. Oversized Elements
Use oversized responsive buttons with large labels for ease of input inside a moving and shaking car. This will help reduce the number of missed taps by a human finger.
4. Restrained Interaction
Assume that the user is restrained by a seat-belt and their access to the screen is somewhat limited by the belt than otherwise.
5. Distance of operation
A user that is fastened by a seat-belt may be held at twice the distance away from the screen than normal circumstances.