A six year old NITI Aayog roadmap on ethanol blending shows that the Society of Indian Automobile Manufacturers (SIAM) recommended continuing E10 petrol as a “protection grade” fuel even after the rollout of E20, warning that removing the lower ethanol option could create compatibility, safety, fuel efficiency and drivability problems for the existing vehicle fleet.
The recommendations, included in Annexure D of NITI Aayog’s 2021 Roadmap for Ethanol Blending in India: 2020–25, were submitted during stakeholder consultations as India planned a phased move to higher ethanol blends. SIAM argued that countries transitioning to higher blends had maintained lower ethanol options and urged parallel dispensing of E10 to protect legacy vehicles.
SIAM warned that retrofitting older vehicles to run on higher ethanol blends would be a “mammoth task” because of the diversity of vehicle variants and fuel system configurations. The body cautioned that discontinuing E10 could render many vehicles “neither materially compatible nor efficiency/performance optimised,” risking material degradation, fuel seepage, safety issues, poorer fuel economy and drivability problems — concerns it said would particularly affect low powered two wheelers.
The automakers’ submission also estimated around a 6% drop in fuel efficiency with E20 owing to ethanol’s lower calorific value, noting that hardware and calibration changes in future models could recover some losses but stressing the need to keep E10 available during the transition. SIAM opposed intermediate blends such as E12 and E15, arguing that vehicles on sale were materially compatible only up to E10 and frequent transitions would complicate matters.
The NITI Aayog roadmap, drafted by an expert committee including the ministries of petroleum and road transport, Indian Oil, ARAI and other stakeholders, backed a phased shift to E20 while acknowledging vehicle compatibility measures would be necessary. It cited joint tests by ARAI, Indian Oil and IIP that found up to a 6% decline in fuel economy with E20 but reported no severe engine malfunction or abnormal wear during trials.
The central government has rejected claims of widespread engine damage from E20, saying the blend was introduced after extensive testing by SIAM, ARAI, Indian Oil and manufacturers. Still, the 2021 roadmap records SIAM’s clear recommendation to maintain pan India availability of E10 as a protection fuel as the country transitions to higher ethanol levels.