Justin Bieber was driving under the speed limit during his 'drag race'

Miami Beach - Justin Bieber was driving under the speed limit when he was arrested.

The Heartbreaker hitmaker, who was charged with drink driving, resisting arrest and drag racing in Miami, Florida in the early hours of Thursday morning, was reportedly only driving at 27 MPH in the middle of his "drag race".

A source told gossip website TMZ.com that the 19-year-old star, who was accused of driving between 55 and 60 MPH in a yellow Lamborghini alongside his friend Khalil in a Ferrari for 15 blocks, had a GPS device installed in the rental cars that tracks speed and it proves both cars were only going 27 MPH at the 3500 block of Pine Tree Drive in the middle of their alleged "drag race". 

Only one of the cars broke 50 MPH once during the short rental period and it was after the singer and his entourage left a nightclub a few hours earlier.

Police officers also claimed Justin, who is more than a year under the legal drinking age in the US, reeked of alcohol at the scene but his blood alcohol level was barely measurable at .014.

Meanwhile, Justin finally flew out of Miami on Friday night after refusing to board a private plane that had been organised to take him back to Los Angeles so he could enter rehab after he was released from jail on Thursday.

His security team were forced to sneak him out the back of his rented mansion in South Beach due to the huge amount of fans waiting to greet him.