The Audit Commission slammed the government for failing to remove vehicles abandoned at public car parks - including one that had been forsaken for 11 years.
The watchdog also urged the government to review the parking fees of meters charging the low rate of HK$2 per 30 minutes after finding various districts failed to maintain a parking space availability objective.
While the total number of registered vehicles surged by some 44 percent from about 515,000 in 2006, to 744,000 last year, the number of parking spaces only rose 11.6 percent to 757,000 in the same period, reflecting a severe shortage.
Despite this, 13 vehicles were found abandoned in five government multi-story car parks last November, with 10 left there for between one and 11 years.
The commission also found a roof-top government car park in Kwai Chung, which consisted of 75 parking spaces, had been closed for six years after a security enhancement project inside was completed in October 2013.
The Transport Department argued the car park was unsuitable for use, and that repairs were in fact completed last October.
It also said the facility will be used as a temporary vehicle detention center before becoming a conventional car park.
However, the commission was unhappy with the department's explanation, saying the prolonged closure was unsatisfactory given the huge demand for parking in Kwai Chung. The watchdog also highlighted the department's inability to maintain the objective of keeping 15 percent of on-street metered parking spaces available. According to department data, the territory-wide availability rate fell from 27 percent in 2015 to 19 percent last year.
But the commission found that during the period, the goal was not met in 15 out of 37 districts. Of the districts that failed to meet the requirement, nine had many meters charging the low rate of HK$2 per 30 minutes, instead of the high rate of HK$2 per 15 minutes.
The commission also revealed that meters located close to each other on the same street charged drivers differently.
It urged the department to review the parking fees, in particular those that charge both the high and low rates on the same street.
It also found it problematic that meters in busy districts, such as Causeway Bay, offered a maximum parking time of two hours.
The Transport Department set the maximum parking time for private cars and minivans at 30 minutes at metered parking spaces in core commercial areas, and at two hours on the outskirts. But, a majority of meters on the streets in Causeway Bay and Tsim Sha Tsui offered two hours of parking.
The commission also recommended the installation of electric vehicle charging stations at car parks in Aberdeen, Kennedy Town and Kwai Fong.