Designing a journey
When designing for a complex journey, a lot of things have to be considered. Especially when the car is involved.
Because the car is such a complex device and users should be focused on the road while driving, safety should always be a top priority. At least for as long as the car has a steering wheel. I've found it to be essential to take a good look at the journey your user experiences and if you can design to get tasks completed outside of the car. Since you want to avoid having your user do complex tasks while driving.
My research has found that even though speach, gestures or touch sounds or feels simple, the user is always mentally occupied with the task or command that was given. And since the Tesla Model S has very few buttons to interact with or get tactile feedback from, a user always has to confirm a task by looking at a screen. Which is dangerous.
To try and minimize this behaviour, we have to prioritize screens, buttons and actions for our users. Humans prioritize by proxomity and will tackle what is closest to them first. Or what they perceive as the biggest threat to them. In the car, it's no difference. From the drivers perspective, the steering wheel is the closest object a user has interaction with. It's already in their hands and is the main reason they are in the car, to drive. Next up is the Instrument Cluster. The screen which helps users see core functions of the car that directly impact driving (mainly speed and navigation). The Main Computer Unit is the third priority.
Layers of interaction, humans prioritize by proximity.
In the complete travel experience, the car is rarely the only device users use to travel. A phone often helps them find the right route or where the traffic jams are at. It's very important to know the user's journey and what they're using to get from A to B. Some users don't check traffic information at all, and some find it very important and check it religiously throughout the day.
Therefore it's important to see the car as the only must-have device in the journey. A car is used for lots of ways and not always will users have access to different devices. I would advise to make your design work without the necessity of another device.
The Instrument Cluster displays a notification upon arrival.
As mentioned before, the car is a very complex device. Therefore users might not always understand all functions and systems that are in the car. In this project, I've found users are confused when it comes to battery saving or keeping a healthy car battery. Some users where convinced that heating their car would improve battery life and performance, while others laughed at the idea.
It's important as a designer to know what is actually working and communicate that clearly to the user. It's important that your users get the concept and can answer the 'why am I doing this?' question. While user testing you could ask what a user expects to come next while performing a task. Or just plainly ask the 'why are we doing this again?' question.
When it comes to visual guidelines, there are a couple of tips I'd like to give and have you thinking about when designing a journey where a car is involved.
Big tap targets
Make sure to have big tap targets. A bumpy country road is the ultimate example, but a highway is often quite bumpy too. Users are not that accurate in tapping while in the car. So make sure your buttons are big enough, especially vertically. I would recommend your button to be at least 180 x 250 pixels on a 300 dpi screen.
MIT has done a lot of research on finding the right typeface for the job. Realise your users often only glance at the screen in the car and don’t have the time to read every letter carefully. Readability and contrast makes all the difference when trying to read the information in a split second.
Unfortunately we didn’t get to design different UI’s for day and night situations. However, this is a very real context and something that definitely needs design attention. The Tesla’s big screen is a large lightsource and can become a distraction while driving at night when using colors that are too bright.
Check for confusing calls to action
As mentioned above, users often use a car interface in glances. Therefore it’s essential that your design has clear calls to action and an interface that is easily scannable. Check any given screen for elements that are drawing attention unnecessarily and remove them if possible.
Join groups with users
There is a big Tesla community on both Facebook and LinkedIn. Joining them is a continuous source of inspiration and keeps you thinking like users. If your target audience has a community you can join, it’s likely to be helpful. •