Petrol has become cheaper by one rupee 42 paise a litre and Diesel by two rupees one paise per litre. It includes state taxes. The new prices came into effect midnight last night.Petrol will now cost 61 rupees 9 paise in Delhi, 64 rupees 97 paise in Kolkata, 65 rupees 70 paise in Mumbai and 60 rupees 65 paise in Chennai. For diesel, the consumer will have to pay 52 rupees 27 paise per litre in Delhi, 54 rupees 57 paise in Kolkata, 57 rupees 47 paise in Mumbai and 53 rupees 73 paise in Chennai. In a statement, Indian Oil Corporation said the reduction in prices of petrol and diesel has been effected following decline in prices of pertrol and diesel in international market and changes in Rupee-Dollar exchange rates.Meanwhile, Public sector Oil companies have slashed the price of non subsidised cooking gas by over 50 rupees per cylinder. In Delhi, now it will cost 487 rupees per cylinder, in Kolkata 514 rupees, in Mumbai 485 rupees and in Chennai 499 rupees 50 paise per cylinder.However, the price of subsidised cooking gas has gone up marginally by about two rupees. In Delhi, it will now cost 423 rupees 9 paise per cylinder, in Kolkata 425 rupees 9 paise rupees, in Mumbai 447 rupees 23 paise rupees and in Chennai 410 rupees 59 paise per cylinder.