When we only had that many (I'd hate to count 'em now but we're a car family through and through, so it's destiny to have a ton) I had the over the door sleeve (from WalMart) that held 50 or 100 cars. it was a pain to put them in only to have DS constantly take them in/out. I finally trashed it and resorted to a bucket.
This weekend we're working on organzing and sorting in Lexman boxes from iKea. One is for lego's; one for trains; one for airplanes; one for cars. Except...i was putting cars in the cars box and DS exclaimed: "Those are my car show cars!" So...some of his cars apparently are "regular" cars and some are "car show" cars.
Since your DS plays with them so much i'd just leave them in a box!
Mom to Will