This report examines the characteristics of historical data for vehicle fires in New Zealand parking buildings from 1995 to 2003, evaluates the probabilities of such fires using event tree analysis, and presents a cost-benefit analysis model for the provision of sprinklers in parking buildings. The historical data are filtered from New Zealand Fire Service FIRS data and provide the relevant probabilities for the event tree model which considers the type of parking buildings and different vehicle fire spread scenarios. The results from event tree model are applied into cost-benefit analysis model, where the cost-benefit ratio measure is used and annual cost avoidance of vehicle fire damage by sprinklers in the parking building is identified as the benefit. A case study is finally performed for a public parking building with a total floor area of 30,000 m2 using Monte-Carlo simulation in the @RISK programme. It is found that on average, there were 12 vehicle fire incidents each year in New Zealand parking buildings. Multiple vehicle fire incidents accounted for approximately 3% of such fires. Deliberately lit is found to be the leading cause of vehicle fires in New Zealand parking buildings (26.7% of all fires). It is concluded that annual vehicle fire frequencies in New Zealand parking buildings are generally lower than those in buildings of other occupancies, and an economically automatic sprinkler system does not justify itself in a parking building situation from the building owner’s point of view, based on available data collected during this research. This appears to conform to the requirements for sprinklers placed by the acceptable solution in New Zealand Building Code. Annual usage ratio is found to be the most critical factor in determining the cost-benefit ratio, according to the sensitivity analysis in the case study. When an automatic sprinkler system is not provided in a closed parking building, it is recommended to have an effective smoke control system to provide tenable conditions for occupants and fire-fighters in the event of a fire; this is also mandatory in the prescriptive acceptable solution in New Zealand Building Code.