Das Auto ist ein Fahrzeug.

Because Auto is a neuter noun in German. German nouns have grammatical gender, and each noun takes one of these articles in the singular nominative:

• der = masculine
• die = feminine
• das = neuter

So you learn the noun together with its article: das Auto.

Because Fahrzeug is also a neuter noun. The indefinite article for a singular neuter noun in the nominative is ein.

Compare:

• ein Mann = a man
• eine Frau = a woman
• ein Auto = a car

So ein Fahrzeug is correct because Fahrzeug is neuter.

Ist is the third-person singular form of the verb sein, which means to be.

So:

• ich bin = I am
• du bist = you are
• er/sie/es ist = he/she/it is

Since das Auto is singular, the verb must also be singular: ist.

The sentence follows a very common German pattern:

subject + verb + complement

So here:

• Das Auto = subject
• ist = verb
• ein Fahrzeug = complement

This is very similar to English: The car is a vehicle.

In a normal German main clause, the finite verb usually comes in second position. This is one of the most important word-order rules in German.

So in:

Das Auto ist ein Fahrzeug.

the verb ist is in the second position, after Das Auto.

If you changed the order for emphasis, the verb would still stay second:

Ein Fahrzeug ist das Auto.

That sentence is unusual in meaning and emphasis, but the verb rule is the same.

Both are in the nominative here.

• Das Auto is the subject, so it is nominative.
• After the verb sein, German normally uses the nominative for the noun that identifies or describes the subject.

So in this sentence, ein Fahrzeug is also nominative, not accusative.

This is similar to English grammar in sentences like He is a teacher.

Because all German nouns are capitalized.

So:

• das Auto
• ein Fahrzeug

This is a standard rule in German, not something special about this sentence.

German does not change the indefinite article based on whether the next word begins with a vowel sound. English has a and an, but German does not work that way.

Instead, German changes the article mainly based on:

• gender
• case
• number

So ein Fahrzeug uses ein because Fahrzeug is singular, neuter, and nominative—not because of its first sound.

Yes. Ein Auto ist ein Fahrzeug is also correct.

The difference is mainly in nuance:

• Das Auto ist ein Fahrzeug can sound like you are talking about the car or making a general statement with a definite noun.
• Ein Auto ist ein Fahrzeug sounds more clearly like a general statement: A car is a vehicle.

Both are grammatically fine.

The period shows that this is a statement.

If you want to turn it into a yes/no question, German usually puts the verb first:

Ist das Auto ein Fahrzeug?

So:

• statement: Das Auto ist ein Fahrzeug.
• question: Ist das Auto ein Fahrzeug?

A simple English-friendly approximation is:

• Auto ≈ OW-toh
• Fahrzeug ≈ FAHR-tsoyk

A few pronunciation notes:

• au in Auto sounds like the ow in now
• z in German is pronounced ts
• eu in Fahrzeug sounds like oy

So Fahrzeug is roughly FAHR-tsoyk.

It is a general word meaning vehicle. It can refer to many kinds of vehicles, not just cars.

So the sentence is saying that a car belongs to the larger category of vehicles:

• Auto = car
• Fahrzeug = vehicle

That is why the sentence makes sense as a classification.