A 23-year-old woman driving a Rolls Royce has been charged after allegedly crashing head-on into a Mercedes in the early hours of the morning while drunk.

The 52-year-old man behind the wheel of the Mercedes was trapped in his car and had to be freed by firefighters.

The crash happened on New South Head Road in the upmarket Sydney suburb of Rose Bay about 3.30am today, police say.

He was treated by paramedics and rushed to St Vincent’s Hospital in a stable condition.

The Rolls Royce driver was not hurt, but was allegedly drunk.

She was arrested and taken to Waverly Police Station after failing a breath test.

Police alleged she refused to undergo a breath analysis. 

She was charged with causing bodily harm by misconduct, in charge of a motor vehicle and refusing or failing to submit to breath analysis.

She was given conditional bail and will appear at the Downing Centre Local Court on August 15.