Cribbing from my previous reply in a different thread...
As I understand it, the truth is that all vehicles sold/registered within the state of California MUST display a label that states that the vehicle passed the EPA emission requirements for the year at the time of manufacture. Furthermore, the label MUST also state that the vehicle passed the California emission requirements for the year at the time of manufacture.
On a normal US made car, that's not an issue since, all vehicles made in the US have that label/placard. Though there may be older year models that meet EPA but not California emission requirements.
Enter the Delica. (Hum along with your own rendition of Metallica's Enter Sandman)
So, the JDM Delica does not have the sticker, since Mitsubishi never intended to sell this vehicle in the US as it's configured. But, what about the USDM Mitsubishi Van? Well in that case, that specific engine (gas, not diesel) in that specific configuration (2WD not 4WD) in that specific Model was tested and labeled.
So, how do you register your Delica in California? You MUST have a label that states the vehicle passed the EPA & California emission requirements for the year at the time of manufacture. How do you get the magical sticker? You take your car to the ONLY testing lab in the state of California and give them a lot of money ($4k) to have them spend 12-16 weeks to add a
diesel particulate filter and run some "tests" to then put a magic sticker on your vehicle.
Once you have that sticker, it's a cake walk to register...
Now, you can get "lucky" by going to a sympathetic independant verifier, a sympathetic DMV (that's 4Wheeler's suggestion), by having a sympathetic CHP inspector, by having it already registered in CA, by smiling a lot, etc...
BUT when (not if) the DMV decides to crack down on the JDM import world, no sticker... No registration.