Twenty thousand motorists have been caught speeding by a new fixed speed camera since it was installed a week ago on Western Australia's Mitchell Freeway.

Most of those drivers will not be penalised because the Police Commissioner Karl O'Callaghan says he will not issue infringements for the camera until tomorrow.

However, three cars have been seized and their owners charged with reckless driving.

A 28-year-old man from Mt Nasura, who was driving a Holden Commodore, and a 23-year-old man from Tapping, who was driving a Mitsubishi Magna, are alleged to have been drag racing on the freeway on Sunday morning.

They are alleged to have been travelling at 199kph and 176kph respectively.

A 23-year-old man of Gosnells had his Nissan sedan seized after allegedly speeding through the same camera on Friday.

They will appear in the Perth Magistrates Court in January.

The Commissioner says he is incensed that the camera recorded 12 people travelling at 45 kilometres an hour over the speed limit.

"You can expect maximum effort into finding these people and finding people who break the speed limit and other offences over the Christmas period," he said.

"Don't whinge if you get an infringement notice."

Mr O'Callaghan has also launched the 2011 Christmas Traffic Campaign.

"The sad fact is that with around 190 road deaths being recorded during each of the past few years, more than 10 families will face losing their loved ones between this Christmas and the New Year," he said.

He says WA Police are also running a competition encouraging the community to embrace the road safety message by creating captions for road safety photographs.