This connects to something bigger than one letter. E20, the ethanol-blended petrol now standard across India, has a live mileage dispute attached to it — YouTuber Sourav Joshi's claims about reduced mileage on E20 fuel have been circulating and disputed by manufacturers including Mercedes-Benz. Kejriwal's letter to Modi, sent a day before his noon press conference, is riding that wave rather than starting a new one.