2 cars left, plus #18.
#11 - 1st shown in Zagreb, former Yugolslavia. This car is featured in a book that is also in someone else's shelf
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#12 - Italian, Puch-engined. The 2nd name of its builder sounds like the plural of an Italian 1st name (like 'Roberti', 'Giuseppi', ...)
#18 - 5 letters: _ _ _ _ T. Let's play hangman.