A used diesel vehicle can be registered in CA once it has 7000 or 9000 miles on it. I forget which.
A digital odometer reprogrammer box runs a bit over $400 on E-bay last I checked.

Hmm...You know I tracked that one down a while ago and I couldn't seem to find it now, but it wasn't the DMV, it was the California Air Resources Board.

As for mileage, the car has to have over 7500 miles on it, at point of sale.
www.dmv.ca.gov/about/lad/...eg/text.pdf

Anyway, good luck!

funny , I was just on the CA DMV site a little while ago, because I'm planning on "importing" a used diesel trooper from another state. basically, in CA you can only import a new vehicle (gas or otherwise) form another state if it meets CA SMOG rules. i.e. if it says on the emissions tag under the hood that it's legal in CA. most cars have special versions for CA, and different version for the rest of the US (i.e. 49states). some cars are not available for CA at all. if the car has over 7500 miles on it, then you can import the car as "used". I have heard that some DMV offices get very suspicious if you're a resident and try to register a used "new" car with barely over 7500 miles on . there are some exemptions, like military employees, divorce or if it's a replacement car for one that was lost/stoles in another state. also, the state excise board tries to crack down on people who purchase "new" cars outside of CA and "age" them before bringing in. something else to worry about if you purchase a used "new" car outside CA.