Fire and Emergency says the occupants of a ute which caught fire south of Whanganui on Thursday escaped without injury.
Fire crews were called to State Highway three near Whangaehu at 8am.
Images on social media show the front end of a white Ford Ranger fully engulfed ahead of fire crews arriving on the scene.
A truck driver passing by, Aaron Isaac said he was unable to stop to help because his vehicle was loaded with hay bales and he didn't want the fire to spread.
It reminded him of the importance of carrying a fire extinguisher on any vehicle, he said.
"All of our trucks have them. It could be something minor, you don't want it to go bigger all of a sudden and same for any other road user you might be able to stop and help," Isaac said.
"For the size of a small thing under your seat or in your boot, you could have stopped a rather big problem. Every vehicle should really have one in it."
Ute fire on State Highway 3 near Whangaehu on 18 January, 2023. Photo: Supplied / Grace Greenwood
Bronte Sharp-Vincent said he could see thick black smoke over the hill as he approached the scene at about 8.10am.
He said he felt the heat of fire as he pulled into the right hand lane and as he drove past the vehicle its tyres began to explode.
"I saw what looked to be the two occupants from the vehicle out of the vehicle and standing 50 or so meters up the road, obviously in a distressed state," Sharp-Vincent said.
Fire and Emergency said two appliances from Whanganui worked to extinguish the blaze and confirmed the driver and a passenger were uninjured.
Ute fire on State Highway 3 near Whangaehu on 18 January, 2023. Photo: Supplied / Bronte Sharp-Vincent