Car-sharing operators' three biggest bugbears are a need for parking spaces, unauthorised use of their designated lots and a lack of awareness about what they do.
Which is why Car-Sharing Association of Singapore president Lai Meng is encouraged after the Government announced last week that it will make available more parking lots in HDB estates for shared cars.
While high demand has made it very difficult for providers to secure spots near new public transport links in recent years, Mr Lai said it is critical to provide shared cars near hubs like MRT stations as people who live nearby are less likely to own a vehicle.
The association has found that car-sharing locations near public transport hubs have the highest rate of use.
Mr Lai said another challenge to tackle is unauthorised parking in shared car lots. "If the next user coming to get the car cannot find it at the usual place, it compromises efficiency," he said.
He added that there is also low awareness of car sharing - a membership service allowing people to share a fleet of different cars, with "pay-as-you drive" rates.
Shared car lots are typically located on the higher levels of HDB multi-storey carparks and while sharing firms do their share of marketing, word of mouth is still the biggest source of recruitment.
Mr Lai, also the managing director of car-sharing firm Car Club, said it would help if there were signs alerting residents to shared cars at street level and designated parking lots at lower levels to improve visibility.
A shared car is used an average of three to four times on a weekend and two to three times on weekdays.
There are four providers in Singapore. Car Club, WhizzCar and electric car-sharing outfit Smove are conventional operators, while iCarsClub offers peer-to-peer car sharing, allowing members to rent out their private cars.
Together they have over 100 locations, around 300 cars and 9,000 members - up from about 4,800 in 2010. Mr Lai is hoping to grow the number of shared car locations to between 300 and 400.
Mr Tony Dufays, regional director of UITP, the International Association of Public Transport, believes car sharing will reduce increasing demand for car ownership in Singapore as it offers an alternative.
He noted that all other transport modes become secondary once a family owns a car, whereas the "pay-as-you-drive" principle of sharing leads to mobility behaviour that is not dominated by the car.
"It is exactly the key allowing citizens to choose or remain with sustainable transport modes like public transport, walking and cycling," he said.
"It allows people to have an occasional use of a private car when other sustainable transport modes can't serve their purpose."
Car sharing also helps families avoid the financial burden of owning a car, he added, while it is also important for car-sharing operators to develop links with public transport operators and the Land Transport Authority.
Bank employee Bill Choo, 35, joined Car Club last December and uses the service about once a month to take his family to places such as Labrador Park.
The Telok Blangah resident likes the convenience of having a car when he needs it, without having to worry about costs like insurance, and feels it is also another option for new parents.
"For single people, taking the MRT is no problem," he said. "But for parents with strollers, it's quite terrible. With car sharing, instead of buying a car, people may think they might as well rent one."