Originally Answered: Can you still drive on route 66?
Technically, no. Route 66 no longer exists, the route number was decommissioned.
However, some portions still exist and are labeled "Historic US 66." Other portions have been neglected and are not passable. So, the old road does not exist from end to end, but there are still many sections of Historic 66 that you can drive on between Chicago and LA. This is fun because the old US Highways run through towns, not around them like the Interstates. You really see America like that.
Start some research:
No, you do not need an old car. It's a road like any other, there are no regulations restricting you to "old cars" or anything like that. That said, taking the old one could be fun, but make sure it's reliable, as there are desert sections.