[Babul]

if the vehicles amount to be checked is small enough, it could be done with a timer. there is no need to loop rhrough all players tho, but i agree at avoiding timers whereever possible.
you could use the OnPlayerStateChange() callback and check if a player enters a certain VehicleModelID and trigger the (custom) eject-player routine. this could be possible w/o loops and w/o cycling through maybe 20 (forbidden) vehicles by setting a gVariableForbiddenForACertainTeam[212]=1; - if its set, then simply eject that player...