There are 6 cars, 2 motorcycles and a Kart at my house and they all run. 3 of the 6 are daily drivers.
My thought is it's very easy for the cars to own you.
If I actually had more space I might have kept the Datsun 1200 project/parts cars; instead I took everything I needed and passed them on. These things have a bad habit of morphing into "I have 75% of the parts needed to get it running" and we all know that last 25% is the killer. The lack of space to do this is very self policing.
It also helps that I have a friend who hoards motorcycles as an example of what not to do.
To me the ideal is a daily driver, a race car/track car, a tow car and maybe a Friday fun car/classic car. After that it becomes a full time job keeping them going.
My .02
Six, half run, half in storage in need of Major Work. One of the runners needs Major Work to be really enjoyable.
However, we've got nothing on blocks in the front yard, and nothing even sitting immobile on the property, and fortunately that jibes with my wife's requirements. Keeping it that way did mean passing on a Jag XJ6 that I'm going to lament for a long time, but things are good.
I'm short on motorcycles. Maybe when the garage is done.
I have 5 right now, 4 running and 1 project.
Personal opinion you get to have one non running car at a time, that you are actively working on, then its a collection. If you ever say you are buying something to get ahround to and you don;t within say 2 years you are hoarding.
Three vehicles and an enclosed trailer. And I live in a high-rise apartment.
I have stuff parked all over the place.
I'm just buying them before the hoarders get 'em.
I'm being called out here, and I don't like it. 
7 . . .. that my wife knows about. . 
6 here at home, 3 daily ready family cars, one dump run/tow pig/beater van, one track car and, the last is a project car. There is a second project stashed at my mother's but it has been gifted to someone else and they just haven't collected it..... so 6.
Ugh, this is timely...
If you have parts cars you've never seen, in other states, is that bad?
