National Green Tribunal today questioned Delhi government's odd-even formula for vehicles to check pollution, saying it may not achieve desired results. The Tribunal said the odd-even formula may make people buy two cars. <br/><br/>The NGT has ordered that no new diesel vehicles would be registered in the national capital in the backdrop of rising air pollution and smog levels in the city. The tribunal has also directed the central and state government departments to not purchase any diesel vehicles. <br/><br/>The Delhi government had last week decided that private vehicles with odd and even registration numbers will ply on odd and even dates from first January next year for two weeks.