Firefighters pulled the 17-year-old boy from the front passenger seat of a Subaru that collided with a tree in Orange about 12.30am on Friday.
He was airlifted to a Sydney hospital but died hours later.
The male driver, also 17, and a 14-year old girl seated in a back seat were unharmed.
Police said the driver was taken to a local hospital for mandatory testing and is now assisting them with inquiries.
Specialist police will investigate the circumstances of the crash but witnesses have been urged to come forward with any dashcam footage.
Meanwhile, firefighters have spent nearly four hours extinguishing a semi-trailer that exploded on NSW's northern coast late on Thursday night.
The B-double caught fire on the Pacific Highway, blocking two lanes outside Pimlico, as it was hauling six tonnes of aerosol spray cans, as well as gravel and cane mulch.
The cans ignited and caused a large explosion with the truck driver and another motorist making it to safety as the fire took hold.
Multiple fire and rescue units were involved in putting out the blaze, which included numerous spot fires around the scene caused by the cans.
An absorbent barrier to protect the environment from liquid run-off and 400 litres of spilt diesel fuel from the burning rig, which was destroyed in the fire.
Traffic flow was limited to one lane northbound during the three-and-a-half-hour operation.
The cause of the explosion has not yet been determined.
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