The new year has delivered Sydney motorists a milestone at the bowser, with petrol prices falling below $1 a litre for the first time in six years.

Metro Petroleum is leading the charge, dropping the price of E10 to 99.9 cents per litre at three of its Sydney stations in Tempe, Revesby and Blakehurst at 1pm on Tuesday.

About 20 per cent of all fuel sold in NSW is E10 unleaded.

Metro Petroleum's pricing officer Elie Dib said he expected the price to hold for a week.