The Regular are your day-to-day response Gardaí. They deal with 999 calls and conduct criminal investigations. They also work in community policing to ensure the safety of the communities of Ireland. They use a fleet of Hyundai i40's, i30's and Ford Focus' vehicles to assist them in completing thier duties.
An Garda Armed Support Unit may be called out to support local Garda officers in certain high-risk operations. This primarily involves offering armed assistance to otherwise unarmed Gardaí who are dealing with an incident in which firearms or other weapons (knives, etc.) have been produced. They also work on providing tactical support to other gardaí carrying out searches, carrying out high visibility static & rolling checkpoints and other operations to counteract the movements of criminals and overt armed airport & port patrols to counter terrorist attacks and so much more.
The Garda National Drugs and Organised Crime Bureau (GNDOCB) is a specialist agency that investigates domestic and international drug trafficking. Its remit also includes strategically reducing the demand for drugs in conjunction with other government agencies. They use a wide variety of unmarked vehicles.