Assume cost of petrol car =Rs3,00,000. Diesel car=300000+200000=5,00,000 Rs. Loan to repay is 12%. So on petrol car= 36000. On diesel car loan repayment is = 60000. Fuel cost for 15000 km for petrol car is: 15000km * Rs77 / 12kmpl = Rs96,250. and for diesel car is = 15000km * Rs 65 / 18 kmpl = Rs 54,166. NOW total expenditure with petrol car per annum = loan 36000 + fuel 96250 + maintenance 8000 = Rs 1,40250. Total expenditure with diesel car = 60,000+54,166 +12000 = 1,26,166.