Govt may issue guidelines for 'flex-fuel' vehicles by Oct By IANS | 5 Views Petrol. . Image Source: IANS News New Delhi, July 4 : Auto companies may soon be asked to manufacture passenger and commercial vehicles that run on multiple fuel configuration aimed at reducing the use of polluting fossil fuels and cutting down harmful emissions. New guidelines for use of flexible fuel vehicles (FFVs) using flex engines is expected to be issued by the third quarter of current year (FY22) that would specify engine configuration and other changes required in vehicles to conform to stipulated changes in fuel mix. The government is also working on an incentive scheme to promote manufacture and use of flex engines in vehicles. The details would be specified when policy in this regard is unveiled.