Quote Originally Posted by John_Douglas View Post
If you're a monster who eats cars, you might say:

я хочу машины

"I could really go for some car right about now."
Not really. Such monster can say Я хочу металла, Я хочу пластмассы, Я хочу колес. You can use only something uncountable in singular from here (and the word машина doesn't fit). We don't say Я хочу бутерброда, Я хочу булочки (not plural nominative!). If something is countable it cannot be used in such way.
In plural - almost anything you want, though Я хочу машин and Я хочу столов do not sound very natural to me. I would not say like that.

Another thing is "мне хочется".
I'd say Мне хочется булочки sounds better than Я хочу булочки, but I'm not sure it is correct.