It started with a traffic stop on the 5 Freeway between Orange and San Diego counties.
Investigators say the driver, Miguel Patron, 41, of Ensenada, identified himself as a police officer in Mexico.
The sheriff's deputy found him to be extremely nervous and asked to search the vehicle.
A drug-sniffing dog was called in, and the meth was found in a hidden compartment.
Patron was booked into the San Diego County jail, with bail set at $200,000.