Concerned residents in Alawa called police after a 4WD burst into flames when two drunken men tried to transform the vehicle into a convertible.

Duty Superintendent Rob Burgoyne said the men, aged 42 and 31, had been drinking when they decided to use an oxyocetylene welder to convert an unregistered landcruiser wagon.

He said the car was engulfed in flames when sparks set the interior alight.

"The car was totally destroyed by the fire, it was [an] unregistered vehicle, it was an older vehicle so not a great deal of value but still a bit of a worry that somebody would do something so stupid," Duty Superintendent Burgoyne said.

When the vehicle became engulfed in flames concerned neighbours called police and the fire brigade.

The suburban Alawa street was briefly closed, and reopened once the fire was extinguished.

"The vehicle was extinguished and eventually the road was cleared and it's unlikely we'll be charging anyone for stupidity."