I wouldn't want to go there, the Vanagon is not a "green" machine.  It
would make sense to say, "Your Vanagon must run at least as clean or
cleaner than the original specs."  I think it is still this way in
Delaware.  They wouldn't know where to start looking for the engine in a
Vanagon.  They have mirrors to look for the catalytic converter and they
usually start about half way up the vehicle and work their way back.  Last
several times, they haven't checked the gas cap or tank like they do all
other gas vehicles.  They sniff the exhaust at idle and at 2500 rpm.  My
Jetta diesel doesn't get checked for any emission related items.  You gotta
love that!    California is a whole other story.

                                                            Jay