An MHK says he's worried falls in petrol prices aren't being passed on to motorists as quickly as they should be.
North Douglas politician David Ashford will ask the Office of Fair Trading chairman about the issue in Tynwald.
He wants to know if the OFT tracks petrol prices to see if consumers benefit from price changes.
He says companies buy the fuel in advance to guarantee its price - but while price rises are passed on falls don't seem to be:
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