I am currently developing an interface for the car control screen, in this screen so far I have to implement such a indicator to give back the response of the turbo status. This status carrying information about the turbo itself ( Turbo On/Off). In last meeting with my supervisor we got confused about the color of that indicator, going directly to the problem, my supervisor convince that when the turbo is activated the indicator have to response with green light and when it deactivate it has to be red light. What I see it something different, I told him that activating the turbo has to be response with red light because the turbo is activated when the driver press such a button near the gear and activation of the turbo can be in such a way dangerous so it has to be red when activate and green when deactivate. So what do you think if you’re the driver , which color will give more clear status ? Thanks in advance

3 Answers 3


This is a very interesting question pertaining to daily life of most people who drive a car.

I'd propose the following reasoning when solving this usability matter:

There are many things happening in a car while someone drives it. Apart from crucial information like speed, engine temperature, fuel amount and few other parameters, the other indicators are more of a suplementory information. Not vital, but definitely useful and having effect on driver's decision making and (hopefully) safety on road. You might want them there, but you don't want them to grab too much attention.

Those of sumplementary nature would be indicators like outside temperature, whether there is ice on road, whether some of the doors are not properly closed, current fuel consumption etc.

I'd like to argue that the Turbo On/Off indication is more of the suplementary nature. Your primary indicators are more important, but you still want it there.

And the reason why you would like your driver to know this information is that, when it is on, the car now has more power and any driver's moves will have a greater impact on the speed and direction of the car. Therefore, your reasoning that the color of the light should be raising awareness and attention (hence red) is correct.

However, it is not the case, that when turbo is off, the car is now much safer to drive. If it has such a feature, most likely it's something closer to a sports car . And since green typically is a color for safety, I'd suggest you to not use green color for turbo on/off at all.

Since Turbo On/Off is not an exact analogy of Unsafe/Safe, the colors Red/Green also are not appropriate either. It is more closer to 'You now have to be really very careful about how you drive this car' and 'You still have to be pretty careful'.

Also, as far as my knowledge reaches, I know that turbos typically become active at certain speeds, revs or power output (correct me where I'm wrong), so the Turbo would come on by itself also, right? Would it be the same indication or you are worried only about setting on/off manually?

Either way, I'd suggest you to use light off (black, or very very dim red) for TURBO OFF, and red for TURBO ON

  • 1
    Thanks for this usefull ideas that I will for sure consider them in my design and impementaion, regarding to the fact that turbo in general automatic activated thats true, but our new system have the option to fully activate/deactivate it at any speed manually using such a button will placed near the gear. Actually I am already printed your answer and dicuss it with my supervisor and we will soonly get the final descision which I will share it with you :)
    – NewUser
    Aug 4, 2014 at 13:38
  • Sure I look forward hearing more about what you will decide in the end Aug 6, 2014 at 8:59

I would go for color for the ON status and no color for the OFF status.

In case of a button on the console this can be any color for the ON status. Just as long as it's consistent throughout the car. Light on = ON. Light off = OFF.

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In case of displaying it on the dashboard (although from your post I recon this will not apply), often next to or inside the speedometer or fuelgauge I would go for green. (I know of some Hondas and Fords who have uses blue as the 'positive' or 'default' color). The color red within the dashboard means a warning or error. The parking break is on or the battery is dead. Orange is a warning like "the car will still function, but you need to take care of the car or it will be a problem".

enter image description here

  • +1. Color coding in the main instrument cluster is highly standardized.
    – MSalters
    Aug 3, 2014 at 23:22
  • Actually using a color for the ON status and no color for the OFF status is considered an old design, the company that I work with have a design standards for the dashbored design that I have to follow.
    – NewUser
    Aug 4, 2014 at 14:04
  • @NewUser figured as much. Aug 5, 2014 at 9:44
  • @Paul I figure as much as I can to solve the problem
    – NewUser
    Aug 5, 2014 at 9:50

I'd definitely go for the red if turbo is on and green when turbo is off. Red indicates higher performance, high RPM, etc, generally something stronger. Yellow indicates fuel saving, something low or neutral. It should be default state for turbo off.

  • thanks for that answer which tells that you agree me with red light for activation. Actually I am doing my graduation project in field of UX in Germany with comapny called Continental Automative GmbH. You can find alot of job offers in there career website. Any help am ready :)
    – NewUser
    Aug 1, 2014 at 13:39
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    Actually I have another question. What exactly do you want to show :) ? I mean, turbo in our cars are almost always ON because it uses fumes from your exhaust. The more RPM, the more fumes and the faster turbo runs. So, I'm not sure if this is a good idea to show only 1 or 0 option. Turbo may have wide range of RPM which automatically rises the pressure level in your intake. Think of it that way. :) Aug 1, 2014 at 14:24
  • @MichałKrztoń: Turbo's are not on at low RPM (not enough boost pressure), and modern engines prefer to run at low RPM to lower emissions. That's why you have turbo lag: as the RPM increases, the turbo has to spin up before the power output increases.
    – MSalters
    Aug 3, 2014 at 23:27

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