I would say that depends entirely on the condition of the car and how trusting you are of it. I put 5000 miles on my 1980 Cadillac commercial chassis coach this summer attending the Gettysburg meet, because the meet was just one part of a much larger vacation I took into Canada and down the Atlantic seaboard. Although there were the pre-trip jitters about taking a 36 year old car on a trip like that, I wouldn't have done so if I had had any genuine worries, and she ended up performing flawlessly.
Of course I don't take trips like that all the time, but obviously it can be done. I don't think the question is how old the car is, but rather how maintained the car is.
Now with that said, my own personal rule of thumb, which of course I do break from time to time, is that if I'm attending a one day event where I leave home in the morning and intend to be back home that same night, the event should be within a four hour drive. If it is a multiday event, then I should be able to drive there in a day.