White and silver cars are cooler than dark ones and need less air conditioning, so fuel is saved and air pollution reduced

Driving a silver or white car is good for the climate. A study a few years ago showed that the interiors of silver and white cars were cooler than black cars. That’s because light colours reflect about 60% of sunlight and make the car’s interior cooler. That in turn means it’s less likely the car’s air conditioner will be turned on, saving fuel and pollution.

Scientists from Lawrence Berkeley National Laboratory experimented by leaving two Honda Civic cars, one silver and one black, in the sun, facing the same direction, for an hour, in Sacramento, California.

Reporting in Applied Energy, they showed that the silver car’s interior was about 5C to 6C cooler than the black car. They calculated that that represented an improved fuel economy of 0.44mpg, or 2%, and that, in turn, would cut carbon dioxide emissions by 1.9% and other exhaust pollutants by about 1%.

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That may sound a trifling improvement, but translated across the US an improvement of 2% in fuel economy in all cars and vans would save millions of gallons of fuel and corresponding CO 2 emissions.

In fact, light coloured cars could be built with smaller air conditioning units that use less fuel and still remain comfortable.

It may seem amazing that something so simple as a car’s colour could make much difference to cutting pollution, but the same principle of light colours has long been used for buildings. White roofs keep building interiors cool on hot days, and those cool roofs help cut the energy used for air conditioning as well as reduce the urban heat island effect in cities.