I am considering moving to California and bringing my '83 240D..I have heard that there really is no emissions or inspection, but a smog test. What should I expect with the smog test they have in CA? Would an old diesel pass easily?

 

Diesel car are excempt from the smog test in California.

http://www.dmv.ca.gov/vr/smogfaq.htm.

 

Ditto
Bought my 300D 2 years ago; no emissions test required for initial purchase or to renew regestration.

About twice in 15 years I have seen them set up a roadside stop and randomly pull Cars off the road in Down Town LA and do a visual inspection to see if the Emissions stuff was disconnected. But, have not seen that in over 5 years.

I was driving a gasser and both times they waved me on buy.
It is not something that they do frequently enough to be concerned.