Renault has been encouraging Romanians to think about buying one of its electric Renault Zoe models with a responsive billboard that reduces the price in line with rising pollution levels. 

The digital "DisCO₂unt Billboard," created by Publicis Romania, was erected in Bucharest, which, according to the TomTom Traffic Index, is one of the most polluted capitals in Europe and the most congested city on the European continent. According to the agency, the campaign, which ran in April, targeted the many Romanians who are put off buying an electric car by the prices. 

The billboard was connected to pollution sensors placed in high-traffic areas around the city, and a custom-made algorithm was created that discounts the price of the car to correspond to levels of pollution at any given time of day. The higher the level, the more the price is reduced. Prices changed every six minutes and anyone could claim the discounted price on the spot using their smartphones and then go straight to the dealership.