if you go to a smog test place that has a 2wd dyno, all they can do is stick the sniffer probe up your tailpipe and rev the engine w/ no load on the engine (tranny in N).
all the smog places are different. some are more lenient than others. the CA DMV computers (which are connected directly to the DMV) at the smog test places can tell if the ECU was recently reset to erase emission fault codes. if they detect this recent reset, the smog tester person can tell you to drive the car around for about 30mi's to allow a retest, or they may just fail you, and the failure gets sent to the DMV and that's bad news. i'm not even sure what you would do if that sort of failure gets sent to the DMV.
