For the first time in Delhi, diesel has become costlier than petrol in Delhi. Diesel prices was hiked all over India for the 18th day in a row on Wednesday since state-owned oil marketers began revising prices from June 7 in line with costs. Petrol and diesel prices at Rs 79.76/litre (no increase) and Rs 79.88/litre (increase by Rs 0.48), respectively in Delhi today.