A convoy of 60 fuel price protesters' vehicles has completed its crawl along the M4 in south Wales as petrol retailers engage in a price war.
Dozens of lorries, buses and cars joined the protest
Protesters agreed to drive at 50mph after their leader was arrested then "de-arrested" for allegedly refusing to move from the second lane, police said.
Following the two-way go-slow between Carmarthenshire and Newport, organisers decided not to blockade oil refineries.
Retailers Asda, Tesco and Esso have cut fuel prices by up to 4p a litre.
BP said later that reductions would be likely at its 400 company-owned stations over the weekend, though it could not specify how big they would be.
Convoy leader Mike Greene, of the Welsh Hauliers and Public Less Tax on Fuel Campaign, said protesters had decided against a refinery blockade on Friday because they believed they had got their message across.
But BBC correspondent Abigail Neal said the protesters did not make the widespread impact they had hoped for, and decided to call off the blockade.
The convoy concluded its return journey to Cross Hands, near Llanelli, at around 1830 BST, with vehicles travelling at about 30mph, Mr Greene said.
He said 50 to 60 vehicles were involved in the protest, but police said the number was changing all the time.
Police had also used the Public Order Act on Friday morning to instruct drivers not to drop their speed below 40mph and to drive only on the inside lane, warning those flouting the conditions would be prosecuted.
However, BBC reporters said the protest had caused tailbacks of up to four miles.
Also on Friday, six lorries disrupted traffic on the M60 by driving slowly from Worsley to Oldham.
Friday is the last of three days of protests by the Fuel Lobby, which wants fuel tax cut. Petrol retailers claimed Thursday's action had little impact.
The demos were timed to coincide with the fifth anniversary of the refinery blockades of 2000.
Mike Greene had earlier told BBC Radio 4's Today programme 99% of people supported the action.
Facts and figures behind UK petrol price rises
Environmental protesters countered the action by hanging banners from a bridge over the M4 reading "Cheap fuel costs the Earth" and "Driving to climate change".
Mark Bradshaw, director of Garagewatch which represents independent garages, said petrol price cuts by the bigger retailers' could put smaller retailers out of business.
A Treasury spokesman welcomed the price cuts and called on oil producers to increase their investment in refining capacity.
However, oil cartel Opec said it was "surprised" Chancellor Gordon Brown was blaming producers, who had accelerated production growth in recent years.
Fuel prices have been rising due to massive global demand and the impact of Hurricane Katrina in the US.
UK prices are among Europe's highest, topping £1 a litre for unleaded in some areas - 67% of the total cost of fuel in the UK is tax.