Commuters travelling to Sydney's central business district are increasingly choosing to leave their cars parked at home and taking trains and buses each morning instead.

The latest government figures show an 11 per cent fall in vehicles travelling to the CBD during the morning peak since 2015, when the government launched a campaign to encourage people to opt for public transport.

In contrast, patronage on all modes of public transport in and out of the CBD between 5am and 10am has risen by more than 10 per cent to 32.9 million trips in the first six months of this year, compared with the same period in 2015.

The pace of growth in public transport patronage during weekday mornings has been greatest between 5am and 6am, which surged by 75 per cent to 634,372 trips in the first half of this year, from the same period two years earlier.