Hundreds of cars queued up to try and get free fuel in a radio station promotion in New Plymouth on Monday morning.

Police had to be called in after a radio station's fuel giveaway caused traffic chaos in New Plymouth.

Hundreds of cars started trying to pack into the forecourt of the Mobil service station, on Leach St, before dawn on Monday attempting to secure a share of The Edge radio station's $10,000 petrol giveaway.

The first 100 people received a $100 fuel card.

The station's afternoon show teamed up with Mobil to find New Zealand's most energetic town and last week Mayor Andrew Judd beat the mayors of Palmerston North and Napier, by singing a song about New Plymouth on air, to win the promotion.

Traffic on the one-way was at a crawl as some motorists tried to nudge their way on to the forecourt and others just tried to work out what was going on.

The promoters underestimated the enthusiasm of the New Plymouth public and had to call in police to help control the eager crowd.

LEIGHTON KEITH/FAIRFAX NZ Senior constable Jason Koch and sergeant George White set up road cones to try and control the traffic in New Plymouth this morning.

Edge TV producer Britta Brandt, of Auckland, said they were not expecting such a big turnout.

"We were not expecting this chaos," Brandt said.

"We had to get them (police) in at the last minute."

Brandt said she had heard Judd sing, describing his performance as "energetic" and saying he might want to think about trying out for X-Factor NZ.

Sergeant George White said numerous calls had been made to the station by people complaining they had been blocked in their driveways and couldn't get to work.

"It wasn't a good time to hold the promotion," White said.

Police helped clear the traffic jam and advised the organisers they should've had a traffic management plan in place.

Judd said while he had appeared in plays and operatics before he would not be singing around the council table.

"If they say talents are hidden, that one is very hidden," he said.

"That was there to help the community, it was a fantastic opportunity to win ten grand's worth of petrol for everybody so I put all of my effort behind it for that reason."

Mike Morresey said he had arrived about 6am after finishing work.

"All of a sudden about quarter-past six she just started moving, it was pretty chaotic," Morresey said.

"There was a bit of in-house fighting, they were all getting a bit grumpy, they were agitated, people were trying to get in, people were swearing because they weren't allowed on the forecourt."

Morresey said it felt "bloody beautiful" to get $100 worth of free petrol.

Kasey Hunt said she arrived about 6.20am after a friend called saying she was already there and it was starting to fill up.

"All of the outside of the forecourt was fill but not the inside," Hunt said.

Colleen Warren said she was pleased to get one of the vouchers after she and her husband arrived early and waited in their car.

"Basically it's really freeing up my week, it means I can have another extra $100 worth of food this week," Warren said.

By 8.30am all of the vouchers had been handed out and the forecourt started to empty but some belated motorists were still pulling up.