When is a car an auto and not a coche?
Pretty sure it's just due to how differenet Latin American countries say it.
Ah! Typo, missed the R off motoR. As you were DL. D'oh!
Personally i think the 'nuevo' should come before the noun as I believe that it'd be common to get a brand new motor, not just one that's new to the owner (so maybe a second hand motor?!)
Like you, I said "el coche tiene nuevo motor" - Duo marked it wrong. ¿Por qué?
I ask the same. A while back I remember a sentence "El coche no tiene batería." So, I thought, just like professions, you omit the indefinite article.