Content designed for a car screen must be legible and glanceable, with a consistent UI and large touch targets that drivers can identify under all viewing conditions.
This section describes how you can:
Make content easy to read
To make sure drivers can quickly scan and understand onscreen content, the content must be presented in a way that’s easy to read while driving:
Display legible fonts
Visually presented primary and secondary text should align with Android for Cars guidelines for font and size. Primary text is typically used for pieces of information required for decision making, such as song titles or contact names, and should be 32dp. Secondary text is typically used for supporting information, such as artist name or call type (such as “mobile”), and should be 24dp.
Limit text length
Text items using the Roman alphabet must not exceed 120 characters, including punctuation and spaces. (Note for reference: The preceding sentence is 101 characters.) Text items in Japanese must not exceed a total of 31 Roman characters, kana, or kanji combined.
Follow contrast ratios for text, icons & background
The contrast ratio for icons, text, and other images must be at least 4.5:1. This requirement applies to any displayed items that convey information, including selected items in rotary inputs and the like. However, if redundant information is provided (such as an icon and text that convey the same meaning), only one element needs to meet contrast guidelines. For rotary inputs, the contrast guideline must be met for the highlight against the background.
Provide glanceability at night
Polarity of content shown during the daytime can be positive (dark text on light background) or negative (light text on dark background), while content shown during nighttime must be negative polarity.
Make targets easy to touch
Drivers can easily get distracted or make mistakes when trying to touch onscreen targets that are too small or close together:
Display appropriately sized touch targets
Touch targets should adhere to the Android Automotive guidelines, for a minimum size of 76 x 76dp. For special cases, width can be slightly sacrificed in favor of height (while keeping overall area the same) to better accommodate up-and-down vehicle vibration.
Avoid touch target overlap
Touch targets must not overlap with one another. The option to zoom can help mitigate overlap issues by separating targets. If possible, allow at least 23dp between touch targets.
Keep UI elements consistent
To help drivers quickly understand their onscreen options, the user interface must be clear and consistent:
Use consistent map icons, terminology & interaction patterns
Icons and terminology should consistently map one-to-one to their functions. Likewise, interaction patterns should be consistent and predictable.
Clarify active & inactive features while in motion
The interface should clearly distinguish allowed from disallowed features – for example, by dimming distracting media content. The interface should also distinguish features that are intended for use only while driving versus those intended for use only while not driving. For example, the search box should be hidden while driving.