New Delhi, July 10 -- As India accelerates the rollout of E20 petrol, comparisons with Brazil, where ethanol has powered vehicles for decades, have become central to the debate over ethanol-blended fuel.

According to a Hindustan Times report, Petroleum and Natural Gas Minister Hardeep Singh Puri last year pointed to Brazil's long-standing use of E27 petrol, a blend containing 27% ethanol, saying the country has not reported engine-related issues because of it. Road Transport and Highways Minister Nitin Gadkari has also cited Brazil's success, noting that the country adopted E100 ethanol fuel years ago.

According to reports, while Rio de Janeiro's ethanol blending model is often cited by policymakers to back New Delhi's adoption, critics...