And another 4p a litre as a result of Opec's oil hike would see petrol selling at an average of 82p a litre. But the figures disguise a disturbing reality that some garages already sell fuel at up to 84p a litre. Arval said in August 2003 the average price of unleaded petrol was 76.15p a litre. But the most expensive garages in Brora, Caithness, Scotland, and Wivelsfield, East Sussex, charged 83.9p.