For self-employed inner Sydney resident Tim Chapman, selling his vehicle and embracing car-sharing was a simple decision.

"I just wasn't driving the car at all, certainly not enough to pay for registration and insurance, and it was just a pain in the neck having to park it," he said. "For everyday use it is better to share a car."

The 35-year-old Surry Hills communications researcher is emblematic of Sydney's embrace of car sharing over the past few years.

About 20,000 residents within the City of Sydney's boundaries are now car-share users, representing about 15 per cent of the residential population.