New Delhi, July 11 -- The government on Friday reiterated that 20% ethanol blended petrol (E20) is a more efficient fuel than E10 or pure petrol , and said moving to the blend required an investment of around Rs.100,000 crore a year over the past several years, financed by state-owned banks. The government also rejected the suggestion to give consumers the option of filling up pure petrol or E10 or E20 on the ground of infrastructure constrains and said doing this would be a "logistical challenge". E20 offers a significantly higher-octane rating, superior anti-knock characteristics, faster combustion, better pickup, smoother acceleration and cleaner engine operation, the petroleum ministry said in a statement issued in the format of frequen...