They weighed what they weighed, I just can't figure out why.
I've never found much use for Ockham's Razor. It only has one blade after all. Who can even think about shaving without a minimum of four? But in light of this rejection of the simplest explanation, here is your answer:
The original owner of this particular E3 just happened to be a
narcotraficante who lived in the Baja peninsula. He had titled and registered the car in California mainly because he frequently traveled north of the border to visit his mistress. She was a US citizen who lived in El Cajon, but the location is neither here nor there.
One day, after having heard that he was going to leave his wife any day now (for at least the 100th time), his girlfriend decided she'd had enough. She drove across the border in the E3, which didn't raise any suspicions because of the local registration. After a few weeks she proceeded to, in essence, petition for custody of the vehicle. Her attorney argued that she was entitled to the car on the basis of her long-standing relationship with the owner. The judge was sympathetic to this line of reasoning and awarded the title to the ex-girlfriend. This case would come to serve as a minor precedent in the famous "palimony" case that was to come a few years later.
Having received the title in her name, the ex decided to sell the E3 out of a mixture of spite and needing some cash. She didn't have too much trouble finding a buyer and the sale was quickly made. But there was something special about this car that neither the seller nor the buyer was aware of: the PO had fabricated secret compartments in the car. One was located in the left front fender and the other was in the right rear wrapping around the gas tank. Not only did the vehicle have these secret compartments, but they happened to be filled with about 30 and 10 kilos of coke respectively.
I'd suggest Rey make like a suspicious border crossing agent and disassemble that car ASAP. There might be an early retirement hidden away in there!