A Victorian man, aged in his late 20s, clocked 158km/h at 4.30am and had his car impounded for 48 hours. Four hours later a South Australian man, also in his late 20s, was caught speeding at 150km/h with a passenger.

Both were travelling towards Adelaide and attempting to overtake other vehicles on the Western Hwy at Windermere, which is zoned 100km/h.

Ballarat Traffic Management Unit Leading Senior Constable Randal Smith said the behaviour of the speeding drivers was aggravated by the large amount of traffic on the Western Hwy at the time.

"It was totally unacceptable seeing there were lines of traffic travelling ... these vehicles were attempting to overtake them," Leading Sen Const Smith said.

"It was a case of doing the wrong thing at the wrong time of year. It's unacceptable at any time."

The motorists, one driving a Ford XR-8 and the other a Mazda RX-8, had their driver's licences immediately suspended for 12 months and were each fined $584.

Leading Sen Const Smith said the men did not tell police why they were speeding.

"They were not thinking about the consequences of what could happen," he said.

"Any mistake could be a fatal mistake."

Since December 18, extra police have been flooding highways, back roads and city streets across the state as part of Operation Aegis, which targets the traditional holiday period road killers _ speed, alcohol and fatigue.

Leading Sen Const Smith said the two motorists were stopped when there was an increased police presence on the highway.

He said it was disappointing that motorists were still flouting the law despite being warned.

"Unfortunately they can be warned but people don't take notice."

A bolstered police presence of more than 3000 will continue to patrol Victorian roads until January 3.