An estimated annual 'tax gap' subsidy of some €16 billion for diesel over petrol has made Europe the world's largest market for diesel cars – but the Volkswagen scandal has put the national tax schemes supporting this industry at risk.“There is no reason to keep subsidising this sector," Carlos Calvo, policy analyst at Transport & Environment, told EurActiv on Monday (26 October). The efficiency of petrol-fuelled cars has improved significantly in recent years, while the diesel industry has reduced its nitrogen-oxide emissions only very slowly.