Vieux = old Ancien = ancient / antique. In the case of the car, both are old yes. But the "ancienne voiture" means specifically that this car is from the 70's,60's or older... It's a nice car that was released many many decades ago. The "vieille voiture" can also refer to the release year, but it kind of implies that the car is a piece of crap or at least it has been quite used. For neuf/nouveau, let's say you buy a phone. The phone is new (neuf), you just bought it. But since you replace your old phone, it's also your new phone (nouveau téléphone). You would say to your friend "regarde mon nouveau téléphone" (look at my new phone) but you would never use "neuf" in this case. Neuf is when you're talking about a specific product that was just purchased. You can use nouveau to speak about a trend, a phone model, etc. I'm not sure if it's clear... It may be difficult to grasp but it's harder to explain :)

Très bien! Merci!

J'ai besoin DE lunettes = la phrase dit littéralement "je ne vois pas bien sans lunettes". (C'est le besoin en général. On ne compte pas les lunettes ici.) J'ai besoin D'UNE PAIRE DE lunettes = si on veut être précis et compter.