The business reporter is from the British Broadcasting Corporation.
According to the RAC, the price of petrol fell in July.
The average petrol price was 182.69p per liter and the diesel price was 192.38p per liter.
The reductions don't fairly reflect the fall in the wholesale price of fuel, according to the NHTSA.
Major retailers should cut pump prices even more.
The war in Ukraine and moves to reduce Europe's dependence on oil from Russia have led to a spike in fuel prices.
Many households are feeling financial strain due to rising food and energy costs.
The price of petrol peaked at the beginning of June, but has since fallen. Fears of a recession in the US and other countries have caused the price of oil to fall to around $100 a barrel.
In July, the price of a 55 liter tank of petrol was cut in half, from £105.29 to £100.48.
Over the course of the month, the cost of filling up a diesel tank went down.
The reductions are the third and fourth biggest in the last two decades.
The falls are still too slow because of the reductions in the wholesale price of fuel.
The price of petrol at the wholesale level has fallen by 20p over the last eight weeks, while the average price paid by drivers has only fallen by 9p.
According to the RAC, petrol should be around 167p per gallon.
The failure of major retailers to slash petrol pump prices in line with the fall in wholesale costs is costing drivers, who are paying nearly $9 a tank more than they should be.
Simon Williams said the retailers should have cut their prices more significantly on a daily basis.
July was a tough month for drivers because of their refusal to do this.
Some analysts think that is not a fair comparison.
"Over the last eight weeks, prices have jumped around; it's understandable if retailers have tried to smooth those differences out in their prices."
There is a lag between wholesale and pump prices. I think we'll see a further 5, 6 or even 7p a gallon drop in petrol prices over the next week or so.
The drop in petrol prices is good news for drivers, but it's not a good sign for the economy, warns Mr. Irwin.
He said that the market is worried about a downturn with people cutting back this autumn and winter.
If there are no signs of a downturn, prices could go up again. They could fall further if the market believes they are.