An end to car washes? Nissan unveils 'world's first self-cleaning car'

Superhydrophobic treatment means dirt and mud simply rolls off the car

Nissan has announced that it is currently testing a new “self-cleaning car” that it promises will make car washes “obsolete”.

The new technology comes in the form of a superhydrophobic treatment that is applied to the body of the car, ensuring that water-based substances like mud and dirt simply roll off the surface.

For drivers who take weekend trips into the country - or are simply tired of the slow build-up of grime - the new treatment could spell an end to costly and inconvenient car washes.

The Japanese car manufacturer says that the paint, which is currently being tested on the recently launched Nissan Note, has “responded well to common use cases including rain, spray, frost, sleet and standing water.”

The company is considering including the superhydrophobic treatment as a paint option with an estimated price of around £450.

Nissan’s methods (which rely on manipulating the physical characteristics of the treated surface) have been known about for decades, but recent years have seen many companies attempting to commercialise the technology, offering sprays and treatments that make ordinary objects waterproof.

Superhydrophobic treatments work by increasing the contact angle of water droplets so that the liquid simply rolls away rather than sticking to a surface.

If you imagine a water droplet as a solid ball then the contact angle is the amount of space between the bottom of the ball and the surface it’s resting on. Liquids ‘stick’ to surfaces when this angle is low (imagined a deflated ball plopping onto the ground and refusing to budge) and roll away when this angle is high.

Superhydrophobic surfaces work by combining two properties - super-roughness at the microscopic level and a low surface energy - to ensure that these contact angles remain high.

The roughness creates tiny pockets of air that 'prop' up the liquid while the low surface energy essentially means there's less 'free energy' to create bonds (for a more comprehensive explanation see this video from TED talks).

Nissan's coating is based on technology patented by American company Ultra-Ever Dry and is currently being tested at the car manufacturer's European Technical Centre in Bedfordshire.