Detectives say they found 42.7 kilograms of the drug and $50,000 in cash after spotting a 27-year-old man place a package on the vehicle's front seat at a park in the city's northern suburbs on Thursday.
A short time later, police also arrested a 37-year-old man on Albert Street in North Perth.
Both men were senior members of the Mongols outlaw motorcycle gang, Detective acting Inspector Blair Smith said.
The drugs are estimated to have a street value of $42m.
"We will continue to investigate members of this outlaw motorcycle gang," Det Insp Smith said.
"We'll deploy every resource at our disposal to ensure the safety of the WA community."
Officers also executed seven search warrants across the Perth metropolitan region during an investigation into several members of the group.
Cocaine and $60,000 in cash were allegedly found at a Hamilton Hill home in the city's south.
The two men have both been charged in relation to the attempted possession of a trafficable quantity of methylamphetamine with intent to sell or supply the drug.
They are also facing one count of laundering property or money from the proceeds of a major offence, with the older man scheduled to appear in Perth Magistrates Court on October 6.
The 27-year-old will face the same court on October 25.
Another 27-year-old man was charged with possessing a prohibited drug with intent to sell or supply, namely cocaine.
He is similarly accused of laundering property or money from the proceeds of major offence as is expected to appear before Fremantle Magistrates Court on August 4.
The combined arrests and seizures ensured the drugs would never reach the streets, Det Insp Smith said.
"This is a significant seizure of methylamphetamine in Western Australia," he said.
The investigation, which began in early June this year, is ongoing.
