Nio owners who refer a friend for a test drive this summer will have the opportunity to paint the walls of the company's battery swap stations.

Battery swap stations, a facility unique to Nio (NYSE: NIO, HKG: 9866, SGX: Nio), are being used in innovative ways by the electric vehicle (EV) maker to drive sales.

After letting a few lucky owners decide the location of some of its battery swap stations last summer, Nio is coming up with new tricks to play with these facilities this year.

Nio has launched a campaign for existing owners to invite friends to test drive their vehicles. Between June 20 and August 28, owners will receive a digital mystery box for every friend they invite to complete their first Nio vehicle test drive.

Each mystery box will contain a gift, and one of the most notable gifts is the opportunity to paint the walls of Nio's battery swap stations.

Here is a rendering of a battery swap station with painted walls that Nio unveiled in its app on Monday.

The lucky winner of the gift can pick a battery swap station in his or her area and have its exterior painted with their favorite elements, such as a view of their hometown, a child's graffiti or a scene from a car gathering with friends.

However, it is worth noting that Nio does not allow users to do the painting by themselves, but will invite professional designers to work with their teams to design and present their ideas on the battery swap stations.

Users and designers will be able to add their own signatures to the paint job.

Nio will provide eight battery swap stations to participate in the campaign, offering one such mystery box per week for eight weeks.

This is the second time Nio has used battery swap stations to strengthen its connection with users and drive the acquisition of potential customers.

From July 2 to September 10 last year, Nio ran a similar campaign in which users received one mystery box for every friend they invited to complete their first test drive.

Nio offered 10 mystery boxes including the right to choose the location of the battery swap station and the right to name it.

On July 15 last year, an ES6 owner from Chengdu, Sichuan province became the first lucky winner to decide the location and name of the battery swap station.

In this year's campaign, in addition to the chance to paint the walls of battery swap stations, other prizes in mystery boxes include Nio Credits and free hotel stays in several tourist cities, including Sanya.

As of June 20, Nio had 981 battery swap stations and 857 supercharging stations offering 4,732 charging piles, according to data monitored by CnEVPost.

The company also has 737 destination charging stations offering 4,354 charging piles and access to more than 510,000 third-party charging piles.