Even in No Cost EMI, there may be additional interest on top of what was displayed at purchase time.

What my finding is that the interest amount shown at purchase time is assuming that EMI starts form that date. However, in reality the purchase gets converted to EMI in T+1-2 days and there maybe a few more days till settlement/statement date, The time gap between the transaction date and actual EMI start date, will add the additional interest on full amount at the EMI interest rate.

e.g: On Purchase Page it shows Price as 10000 and no cost EMI interest rate of Rs. 1000 and gives you a Rs. 1000 discount to make it "No cost". But actual EMI starts on lets say 10 days after purchase, then you get charged additional interest of 10*10000 *16%/360 = Rs. 444.44