A modern car (say, post-1995) will run on lower octane gasoline with reduced performance (power, economy) and no other issues.
Older cars did a lot of nasty things ranging from occasional "pinging" or "ringing" noise and accellerated engine wear to complete engine failure.
Then again, one cannot easily find these days neither a pre-1995 car nor a gasoline with low enough octane number in order to create problems in a car built for pre-1995 standards gasoline.
p.s. it is OK and pretty much advisable to mix some '95 gasoline into '92 in your tank