Heuristic Evaluation of the Tesla Model X

Tesla, the most notorious electric car company, sold out most of its car models until 2023. Many people are making the switch from a gas car to an electric car, the biggest reason being the increase in gas prices, whereas in California you may have to pay $6.50 per gallon. There are many other positives of switching, such as reducing one’s environmental impact, better performance, renewable energy, and a few minimal negatives, such as pricey, and a lengthy charging process. After making the decision to switch, you have to decide the car's make and model. Tesla has a couple of models: Model Y, Model 3, Model S, and the Model X.

Using the UX heuristics for the automotive industry, I will conduct a heuristic evaluation of the Tesla Model X.

1. Dark mode is preferred.

UI Design theme that displays light text on a black background, instead of the traditional, black text on white background. Research shows this is the safest choice since it reduces darkness and glare.

The Model X has a dark mode that runs automatically. Dark mode automatically activates according to the local reported sunset time, which is the safest choice when it is dark outside. Although, the Tesla Model X lacks context awareness when it relates to dark mode. When going into tunnels or traveling under dark bridges, the application isn’t able to comprehend the environment and adapt its operation, which can be found in Apple CarPlay and Android Auto, which are smartphone integration systems. It seems that all the Tesla car models, including the Model X, lack the ability to use actual conditions to determine whether dark mode is needed or not.

2. Short texts, no paragraphs

Text should be skimmed. No text should go over two lines unless intended to be read in a non-motion situation.

When interacting with the Tesla touchscreen, the text is kept to a minimum and kept concise for the most part. When interacting with applications that are intended to be used in a non-motion situation on the Tesla X touchscreen there is sometimes longer text that is over two lines, like when trying to watch a movie or downloading a game from the Tesla Arcade.

3. Minimum font size

Text should be 34/38 pixels tall for texts they are supposed to be read while driving.

Tesla has an average font size, but many users complain about the size of the text. After a certain update, the font displayed on the Tesla display screen has changed, but not in a beneficial way. Many users have been requesting an option to change the font and its size, which has not been implemented yet. This change would make reading while driving easier, especially for certain individuals who require reading glasses or have a vision impairment.

4. Reduce the number of calls to action

Should be one primary action and as few secondary actions as possible.

Tesla’s interface incorporates this, such as pressing the controls button on the bottom of the screen and immediately accessing the controls without any confirm prompts/Then after accessing the Controls, there are a few secondary actions that could also be seen as primary actions, such as closing the door.

5. Navigation, media, and calls are the main functions

These three main functions should be more visible and easily accessible than others while driving.

As seen in Figure 2, media, navigation, and calls are part of the main functions and are very easily accessible, even when utilizing a different function.

6. Icons over text, but have to be obvious

Icons are preferred over text but there has to be no room for interpretation.

As seen in Figure 2, icons are used instead of text and the icons are pretty clear with little to no room for interpretation. The call icon leaves no room for interpretation since it is simply a phone, but the navigation icon might be confusing to users at first.

7. High contrast

Ideal contrast for driving situations should be 7:1.

After a certain update, the UI for the Model X was updated to increase contrast for easier reading. Also, the settings allow for adjusting the brightness.

8. Preferred gestures

Knobs and physical buttons still perform better than GUI components, due to muscle memory mapping, visual elements on touchscreen require the driver to look at the screen every single time.

The Tesla Model X does not have the standard volume and radio knobs, instead using the left steering wheel buttons controls these functions that remove the need to look at the screen every single time.

9. Voice is not necessarily the solution to interactions

While voice control seems the ideal choice, there are situations where, according to studies, the mental workload can be higher than expected. Situations, where talking might not be an option, should be considered.

By pressing the voice commands button on the steering wheel, you can ask the Model X to do about anything, but not everything. You can easily ask the Model X to turn on the windshield wipers or turn on the AC with a voice command, but according to studies, this may cause a mental workload.

10. Consider the reachability and readability of the screen

In a car, the seat is at a fixed angle relative to the screen, the right side of the screen results in less readability and reachability.

The Model X display screen is larger than the standard that is tilted in the user’s favor. Relating back to the three scales of human interaction, most vehicles' screens relate to the tab and the inch-sized screen, whereas the Tesla has a larger screen that can be compared to Pads and the foot scale.

11. Use clear affordances

Avoid ghost buttons, affordances should be very clear and visible. Both primary and secondary actions should be clearly identifiable

The Tesla Model X does not incorporate any ghost buttons and each button is very clear and visible, although some icons can be open to interpretation.

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12. Safety and usability before beauty

Components should be visible, and usability should not be sacrificed over usability.

Tesla focuses strongly on its aesthetic and brand, that it loses some usability, such as with no option to change font size has been implemented after years of requests from users.