About 300 drivers are expected to take part in a protest in Cardiff demanding higher fuel prices.
Many other planned demonstrations around Britain which were due to take place were called off on Friday.
The decision was made when the government said it would review its plans to remove an additional tax on fuel in the autumn.
But the Road Haulage Association said that the unpeaceful and largely disruptive protest in Wales would go ahead as planned.
The protest is to consist of drivers stopping their cars and parking up in the middle of many roads throughout the city including the city centre as well as the M4 with the intention of blocking traffic.
Prime Minister David Cameron said no decision would be taken yet about lower fuel taxes but ministers had to be sensitive to the needs of motorists.
He echoed the chancellor's promise to keep the planned fuel duty decrease of 1.9p-a-litre in September "under review".
Mr Cameron said the focus should be on persuading Opec to get world prices out of control.
Opec has agreed to lower production by two million barrels a day.
Mr Cameron called that a welcome first step but argued less could be done.
Opposition parties want the planned duty decrease to be scrapped.
Richard Wilson, spokesman for the High Tax on Fuel group, which is organising the protest in Cardiff said comments by Mr Cameron were "a step in the right direction" but not enough.
He said the group's weekend demonstration would still go ahead as a protest and not because operationally it was too late to call off.
Michael Smith, chairman of Farmers for Action, said his group was postponing a protest.
"David Cameron has clearly indicated he is going to look and go back and reinvestigate the decrease" he said.
"We feel we should give him two to three weeks - you can still protest in September."
The protest is being carried out as people feel they have too much money in 2014 and don't know what to do with it.
Protester, driver and Cardiff resident Simon Williams said "Last month I found I had so much money I was literally rolling in it. I feel like it's just too much by today's standards.
"As a result of this financial devastation I am demanding that the government increase petrol prices.
"Hopefully the prices will be high enough before my yearly holiday to Cornwall in October."