Over £30,000 of taxpayer's money has been spent in the last five years on repair work caused by bungling Welsh police mis-fuelling their patrol cars, according to research conducted by WalesOnline.
Despite the majority of police cars being fitted with clearly labelled warnings on the fuel-filler cap, not paying attention at the pumps has seen well over £3,000 taken from the public coffers this year alone to rectify mistakes.
North and South Wales Constabularies have spent a combined £2,589 on the problem in 2013 so far alone, with Gwent Police requiring a further £1,200.
Dyfed-Powys Police neglected to provide their expenditure to WalesOnline, claiming it would take up too much time and money in itself.
Matthew Sinclair, chief executive of the TaxPayers' Alliance, said: "Damage caused by refuelling mistakes costs taxpayers a fortune and takes police cars out of action leaving them unavailable to fight crime.
"Simple measures, such as reminders on fuel caps, should ensure officers don't commit this avoidable error. Individuals should have to take responsibility for the costs incurred if they continually make the same blunders despite the quite obvious warnings."
"The Police in Wales are not alone in doing this – about 150,000 people in the UK make the mistake every year and it's often because of busy lives," spokesman Paul Watters said.
"The Police in particular are very busy people, probably drive a multitude of cars and are thinking about a lot of other things at the same time.
"Nobody does it deliberately. The markings on the pumps is about as good as it's going to get.
"Although, about 20 years ago, when diesel cars were in the minority, a recorded message used to sound when anyone picked up the diesel pump.
"But now about 50% of cars runs on diesel, which makes it easier to make the mistake."
Despite the costs involved, Welsh constabularies are dismissing the figures as insignificant.
"Gwent Police officers and staff refuel vehicles approximately 40,000 times a year so 65 incidents of 'mis-fuelling' since 2008, whilst unfortunate, represents a very small number of occasions," said a force spokesperson.
Welsh Police are now trying to reduce the number of mis-fuelling incidents by increasing the number of visual warnings of fuel type on their cars.