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Some time in 2009, California passed new regulations, banning black cars (here's one source) on the grounds that black cars have higher emissions than other colors of cars. The theory is that black cars absorb more heat from the sun, so their A/C must work harder. Is there any truth to this?

And if there is, wouldn't it be beneficial in winter months to have black cars?

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    That would assume (even just for summer) that everyone uses A/C all the times (which may be true in California, I don't know). – nico Oct 9 '11 at 8:25
  • They are certainly hotter without A/C in sunny places... – Sklivvz Oct 9 '11 at 8:46
  • @Sklivvz: To the touch? Or in the cabin? :) Source? (personal experience?) – Flimzy Oct 9 '11 at 17:50
  • @Flimzy: completely personal/anecdotal experience. I am referring to the inside of the car (so the air, but also the interiors). – Sklivvz Oct 9 '11 at 17:53
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    Btw, the proposed regulations never made it to law, primarily due to potential issues with reflective glazing interfering with mobile phone reception and so forth. source. Black cars (nor any other colour) were not to be banned either. – Joel Rein Oct 9 '11 at 22:21
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The "heater" in your car does not actually generate heat itself. It actually takes the heat generated by the engine and passes that back through your cabin rather than venting it outside. So neither heaters nor winter will increase CO2 emissions.

Californians use approximately 1.8 billion liters (472 million gallons) of fuel each year running car air conditioners (do note that this is of 76 billion liters, or 20 billion gallons total statewide - so air conditioners account for about 2.5% of fuel consumption).

The reason that lighter car colours could be used to reduce air conditioning use is that they reflect more incoming light rather than absorbing it and heating up. A black car can heat up by almost 6°C more than a white car.

So, yes, a lighter coloured car would reduce the need for air conditioning, lowering CO2 emissions.

  • Hat tip to @Sklivvz for the metrification. – Joel Rein Oct 10 '11 at 0:25
  • So that leads to the follow up question. Does running the A/C really use up more fuel (at least in a significant quantity)? – JohnFx Oct 11 '11 at 4:37
  • @JohnFx: see the second paragraph of my answer - about 2.5% of fuel use goes to A/C for Californian drivers. – Joel Rein Oct 11 '11 at 5:36
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    @jwenting, I think there's a strong association between darkness of visible colour and infrared "colour" in most cases though - the exceptions seem to be few and far between in my experience. – Highly Irregular Mar 28 '12 at 1:41
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    @jwenting What do you think happens to the visible light that gets absorbed by a black object? Its turns into heat... – Nick Aug 21 '12 at 16:39

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