Learn German: Die Qualität deines Motors ist sehr gut. - Your engine's quality is very good.

This is the genitive case in action! It shows possession, like saying "of your engine". For masculine nouns like Motor, the possessive article takes an -es ending (deines), and the noun itself usually gets an -s or -es ending (Motors).

In English we say "Your engine's quality". Why is the word order different in German?

German doesn't use an apostrophe-s to show possession for regular nouns. Instead, it places the "owned" thing first (Die Qualität) followed by the "owner" in the genitive case (deines Motors). It translates literally to "The quality of your engine".

If both Qualität and Motors are in the sentence, why is the verb ist (singular)?

The verb always matches the main subject of the sentence. Here, the subject is Die Qualität (singular), so the verb is ist. The phrase deines Motors just describes the quality and doesn't change the verb.

Can I avoid the genitive case and use von instead?

Yes, in spoken German, people often replace the genitive with von plus the dative case. You could say Die Qualität von deinem Motor. However, the genitive deines Motors is considered better style and is very common in writing.