The car in Lifford has been moved to Dublin because of a lack of resources there, a garda source has said.
The Garda Representative Association (GRA) says it is aware of unconfirmed reports that garda cars have been moved from other parts of the county as the force copes with stricter financial circumstances.
In previous years garda divisions would be given supplementary budgets when budgets run out but this is no longer the case causing divisions to cut costs.
Another garda source said there were suspicions in the force that unmarked cars were being removed because their absence would not be as noticeable as that of marked patrol cars.
Letterkenny Superinten-dent Vincent O'Brien said he could not comment on matters of budgets or resources.
The loss of resources in the Lifford will raise concerns after a rise in dissident republican activities in the border area this year. Twenty-seven-year-old Strabane man Andrew Burns was murdered in the village of Doneyloop in February of this year with dissident republicans widely believed to be responsible.
Two years ago community leaders in the Lifford area held a public meeting following an increase in antisocial activity and crime in the area as well as concerns about garda resources.
President of the GRA, Donegal Garda Michael Boyce, said any moving of a garda vehicle from a rural area would be disgraceful.
"Crime has no boundaries, it is a national issue and rural Ireland should not be stripped to keep a high profile in urban areas. If that is the case it is disgraceful."
He said that gardaí feared that cuts were having an impact on front line policing. "That is something that we do not want. If it takes X amount to fund the force for one year then X minus Y in the following year is going to have an impact on front- line policing." He said he hoped gardaí would be consulted in the preparations of next year's budgets.