Welcome to GTPlanet. Rather than making a generic thread title, I've edited yours to reflect the question you want to ask. It will make it easier for people to search and find this thread.
The answer is yes, sort of. You, being the lobby host, have the right to decide which cars people can use, and you can see what cars people are using. There *are* certain ways to restrict what kinds of cars people can use, but restricting by year is unfortunately not possible. It will be up to you, taking a look at the cars people are using and making sure they match your criteria.