Elliott Killingbeck was driving home from work when he spotted the blaze on the A3013 Fleet Road on Wednesday (February 8) afternoon.
“I had just come off the M3 and travelling towards Fleet when I came across the car fire,” the 23-year-old said. “So I quickly turned round and blocked the road.
“I was one of two who called the fire brigade as I think the driver also called but I had to update them because he wasn’t sure of the exact location.
“I spoke to the driver and made sure he was alright and that nobody else was in the car.
“He said he’d just bought the car that morning and I said ‘I hope you have it insured’."
Mr Killingbeck, who has recently moved from Farnborough to Fleet, said the driver managed to escape the Ford Focus, which he believed was registered in 2000.
“He managed to get out fine,” he added. “He wasn’t injured at all.
“I think it was the engine that went up in flames but I’m not 100% sure because it was already well alight when I arrived.
“He was already out of the car and I was just closing the road to make sure the firefighters were safe and to keep the public away.
“I’ve come across so many accidents on the roads that it’s become second nature to check everyone is okay and no-one else is in danger.
“It did make me jump when the windows popped and the air bag went off.”
Mr Killingbeck said firefighters arrived at the scene about five minutes after him.
One fire engine from Rushmoor with a crew of four helped put out the flames using two breathing apparatus and a high pressure hose reel. They were at the scene for about 45 minutes.
Hampshire Constabulary said it was called to the fire at 4.30pm and helped with the road closure, adding the fire is not being treated as suspicious.