The 31-year-old was pinned by the leg after a Nissan X-Trail rolled down the driveway of a Kurumben Place home, from which a gymnasium operates, trapping her between the car and garage.

Duty officer with Chifley Police District, Inspector Gerard Powell, said the incident occurred at around 6pm.

He said the driver, a 56-year-old man arrived at the Kurumben Place address and parked his Nissan X-Trail, and for reasons yet to be determined, it then rolled down the driveway, striking the 31-year-old.

As emergency crews worked to free the woman, they also had to support the front wall of the house, which had been compromised in the incident.

Fire and Rescue NSW Bathurst Station Officer Sandy Collins was among the crews who attended and said firefighters worked with Police Rescue to stabilise the brick wall so the woman and car could be removed.

"The wall was very unstable ... it was quite perilous," he said.

Once there was no risk of collapse, the woman was removed, taken by road ambulance to a waiting helicopter, which had landed nearby at a reserve on the Bradwardine Road.

She was then flown to Westmead Hospital, where she underwent surgery, for a serious injury to her leg.

A spokesperson for Westmead Hospital said late Wednesday the woman's condition was "serious but stable."

The Nissan X-Trail has been seized by police for mechanical examination.