There have been at least five fires in Wanganui since February 11.
The police wished to thank the neighbours for their quick response to the Collingwood St fire, which had helped to prevent the blaze from spreading.
Meanwhile, a total fire ban for the region is being considered and will likely be in place at the end of the week.
Fire Service Whanganui area commander Bernie Rush said the ban would mean only gas barbecues could be lit.
Mr Rush said the fire service was concerned about how dry the grass was and were monitoring the situation daily. Any fires in the city area required a permit. There was already a restricted fire season in the rural region. Applications to light a fire were considered case by case by rural fire officers.
Mr Rush said it has been almost two weeks since any decent rainfall in the region, and 100mm of steady rain over three days would be needed to make a difference to the dry conditions.
He is also warning cigarette smokers in cars to keep their butts in the vehicle and not to flick them out the window.
Many fires were lit by a flicked butt, he said.
The last total fire ban across the Whanganui, Rangitikei and Ruapehu districts was believed to be the end of January through February and into March in 2008.
It was in place for five weeks and replaced by a restricted fire season.
The cause of the Rogers St fire in Castlecliff on Friday was inconclusive.
Mr Rush said they suspected it was deliberately lit, possibly in the grass which then spread to the tyres.
There is no electricity in the used car scrap-metal yard.
