While many of the MRT stations are accessible, as are the buses, sometimes a taxi is the best way to get around Hong Kong.
If you are a wheelchair user, the only option for a wheelchair accessible taxi company is Diamond Cab. Thankfully, they are a really awesome company and go out of their way to help – even at short notice!
They use Toyota Noah Welcabs that have a ramp at the back. While the website states that they can carry two wheelchairs, only one power wheelchair can comfortably ride at a time.
The only problem for foreign visitors wanting to book in advance is that you must pay with an international money transfer which has very large fees. But if you don’t you might not be able to guarantee a ride, so you kinda need to bite the bullet.