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What color of a car absorbs the least amount of heat, when exposed to the Sun?
I want to break this question into 3 sub questions :

  1. I know that white reflects all of the visible spectrum, but our Sun is a yellow star, so a yellow car may get less hot when exposed ?

  2. What about the metalic grey which mimics the back of a mirror ?

  3. On the other hand, the most of the heat is maybe not absorbed in the visible, so, in that case, what kind of painture to try in order to reflect, say, infrared ?

Thank you,
Stelian

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  • $\begingroup$ A car with mirror covering would be a possibility. $\endgroup$
    – Pritt Balagopal
    Apr 24, 2017 at 8:19

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For a black car all of the visible light energy turns to heat otherwise you would not be seeing it black.

A reflective car would be a better bet, as long as it also reflects in the uv and infrared.

I live in Greece and used to have a white car. I now have a silvery car, but it gets equally hot as the white one used to, in the sun.

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  • $\begingroup$ Your white and silvery cars are the same type of car? Otherwise I would expect other factors such as window shape/size/inclination.... also to have an effect. $\endgroup$
    – user1583209
    Apr 24, 2017 at 13:16
  • $\begingroup$ @user1583209 one was a renault twingo and the present silvery one a Yaris. $\endgroup$
    – anna v
    Apr 24, 2017 at 15:15
  • $\begingroup$ To be fair most cars are a very glossy black. They seem to reflect quite a bit of the light. Even a matte black has some reflection of visible light. The surface finish and material is really important for the ability to actually convert all the visible light to heat. $\endgroup$
    – JMac
    Apr 28, 2017 at 9:39
  • $\begingroup$ @JMac If you see black it means all visible wavelengths reaching that surface are absorbed. Small reflections from a gloss are not enough. $\endgroup$
    – anna v
    Apr 28, 2017 at 10:38
  • $\begingroup$ this link shows that the surface temperature differences are high, but the inside effect much smaller. tom-morrow-land.com/tests/cartemp . It must have to do with insulation $\endgroup$
    – anna v
    Apr 28, 2017 at 10:45
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White colour absorbes less heat from the sun as it reflects all the wavelengths of light .

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  • $\begingroup$ White doesn't mean it reflects all the wavelengths: only visible ones, with the others behaving in any possible way depending on actual paint material. $\endgroup$
    – Ruslan
    Dec 13, 2020 at 11:17
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I know that white reflects all of the visible spectrum, but our Sun is a yellow star, so a yellow car may get less hot when exposed ?

An object which appears to our eyes as yellow in sunlight is absorbing the blue part of the sunlight and converting it to heat. So a yellow car aborbs more light than a white car - and so heats up more than a white car.

What about the metalic grey which mimics the back of a mirror ?

We would consider an object which reflects ~30%-70% of incident light to be grey - grey means it absorbs all colours uniformly but not brightly. 'Metallic' as a paint finish just means it has optically flat particles in it. So 'metallic grey' still absorbs lots of light to be considered grey.

On the other hand, the most of the heat is maybe not absorbed in the visible, so, in that case, what kind of painture to try in order to reflect, say, infrared ?

You would need to find datasheets from specialist paint manufacturers. One of the most reflective white materials used in optics is Barium Sulphate with 98% reflectivity extending into the near IR, but it is not hardy for use as a vehicle finish.

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