"The manufacturers are also directed to file latest status report about the proceedings taken against them in other countries and explain reasons for not recalling the entire vehicles and why penal action be not taken. Based on further affidavits, the tribunal may have to determine the nature of directions which may need to be issued," the bench also comprising Justice R S Rathore said.
The green panel also directed that all parties be given a copy of Pune-based Automotive Research Association of India's (ARAI) 2015 report on emission tests conducted on diesel cars.
The tribunal had earlier asked ARAI to explain details of tests carried out on diesel cars produced by Volkswagen.
The order had come come after the tribunal was informed that ARAI carried out tests at the instance of the Ministry of Heavy Industries and examined 11 BS-IV compliant diesel vehicles of the German company under different conditions.
The automobile giant had earlier submitted a roadmap before the tribunal to recall over 3,23,000 vehicles in the country fitted with a 'defeat device' meant to fudge emission tests.
A 'cheat' or 'defeat device' is a software in diesel engines to manipulate emission tests by changing the performance of cars.
Volkswagen India had in December 2015 announced the recall of 3,23,700 lakh vehicles in India to fix the emission software after ARAI conducted tests on some models and found that their on-road emissions were 1.1 times to 2.6 times higher than the applicable BS-IV norms.
The automobile giant had admitted to the use of 'defeat device' in 11 million diesel engine cars sold in the US, Europe and other global markets that allowed manipulation of emissions tests by changing the performance of vehicles to improve results.
After the tests by ARAI, Volkswagen India had undertaken to rejig the software by recalling around 3,23,000 vehicles fitted with EA 189 diesel engines which were in alleged violation of emission norms.
The company, however, had said that the recall in India was purely voluntary in nature as it did not face any charges regarding violating emission norms in India unlike in the US.
The counsel for the car manufacturer had told the NGT that ARAI, which is being consulted on the redesign of the software, had approved it for only 70 per cent of the 3,23,000 lakh vehicles.
ARAI, however, had said the Volkswagen had submitted redesigned software for only 70 per cent and was yet to do so for the remaining 30 per cent.
The tribunal was hearing pleas filed by a school teacher Saloni Ailawadi and a few others seeking ban on sale of Volkswagen vehicles for alleged violation of emission norms.