A recent study shows that painting your car a cool color could save you money at the gas pump — or the charging station — by keeping your car’s temperature lower while in the sun. Now we’re not talking about cool as in hip (as in the mind-blowing color of the electric Mercedes SLS AMG E-Cell), but rather a color cool in temperature like shades of blue and violet. The Berkeley Lab’s Environmental Energy Technologies Division compared the efficiency of the air conditioners in two almost identical Honda Civics sitting in the California sun and found that the silver car required a 13% smaller output to cool than the black car.
The researchers who conducted the study parked the two vehicles near each other in a parking lot during the middle of the day in Sacramento, California — where temperatures can reach well over 100°F — and put the cars through five cooling cycles where the air conditioner was shut off for 30 minutes and subsequently the car was cooled to 77°F within 30 minutes. The researchers then measured the roof, ceiling, dashboard, windshield, seat, door, vent air and cabin air temperatures of the vehicles after and during each cycle. On the solar reflective scale (a 0-1 scale that measures the solar reflection of a color, with higher numbers being more reflective) the black car scored a 0.05 and silver car a 0.58.
During the hottest moments of testing the silver car’s roof was measured at as much as 45°F cooler than the roof on the black car. When translated through modeling to corresponding gas mileage savings, it was found that on average a car with a solar reflectiveness of 0.35 will save 1.1% in gas (0.24 mpg) because of its less heat-absorptive paint job. This level of solar reflectiveness would also reduce emissions by 1.1%.
Meanwhile, a silver or white car with a solar absorption level of 0.60 would save 2% in gas and 1.9% in emissions. These numbers also transfer to the charging station – getting a cool colored electric car will help your battery last longer by saving energy in temperature control. Look out, red – there’s a new cool color in town and it could save a significant amount of energy.