CHENNAI Chennai: The price of petrol and diesel in Chennai has remained almost unchanged for the last 248 days. Accordingly, the price of a litre of petrol in the city today is Rs 100.80 and a litre of diesel is Rs 92.39. Oil companies use the current crude oil price in the global market and the value of the Indian rupee against the US dollar as primary variables to determine the price of petrol and diesel on a day-to-day basis.