Το εσωτερικό του αυτοκινήτου είναι καθαρό.

Because Greek usually uses the definite article much more often than English.

• το = the
• εσωτερικό = interior / inside

So το εσωτερικό means the interior.

In Greek, leaving out the article can change the meaning or make the phrase sound less natural. Here, we are talking about a specific interior: the interior of the car.

Εσωτερικό is a noun here, not just an adjective.

It means:

• interior
• inside
• inner part

In this sentence, το εσωτερικό is the subject of the sentence: the interior.

You may also see εσωτερικός / εσωτερική / εσωτερικό as an adjective meaning internal / interior, but in this sentence το εσωτερικό is being used as a noun.

This is the Greek way to say of the car.

• του = of the / the in the genitive
• αυτοκινήτου = car in the genitive singular

So:

• το εσωτερικό του αυτοκινήτου = the interior of the car

Greek often expresses possession or of relationships with the genitive case, where English uses of or 's.

So this phrase could correspond to either:

• the interior of the car
• the car's interior

Because both the article and the noun are in the genitive singular.

Here is the pattern:

• nominative: το αυτοκίνητο = the car
• genitive: του αυτοκινήτου = of the car

So:

• το changes to του
• αυτοκίνητο changes to αυτοκινήτου

This is very common with neuter nouns ending in -ο.

Because it must agree with το εσωτερικό, which is:

• singular
• neuter
• nominative

Greek adjectives agree with the noun they describe in gender, number, and case.

So the adjective καθαρός changes like this:

• καθαρός = masculine
• καθαρή = feminine
• καθαρό = neuter

Since εσωτερικό is neuter, the correct form is καθαρό.

Είναι means is here.

It is the 3rd person singular form of the verb είμαι = to be.

So the structure is:

• Το εσωτερικό = subject
• είναι = is
• καθαρό = clean

Greek είναι can mean:

• I am / you are / he is / she is / it is / they are

depending on context, because in the present tense it has fewer different forms than English. Here, with a singular subject, it clearly means is.

It is an adjective.

It describes the noun το εσωτερικό.

So:

• καθαρό = clean

It is not an adverb like cleanly. In this sentence it is a predicate adjective, used after είναι, just like in English:

• The interior is clean.

Yes, Greek word order is more flexible than English, although not every order sounds equally natural in every situation.

The neutral, standard order is:

• Το εσωτερικό του αυτοκινήτου είναι καθαρό.

But Greek can move elements around for emphasis, for example:

• Καθαρό είναι το εσωτερικό του αυτοκινήτου.

This can sound more contrastive or emphatic, something like It is the interior of the car that is clean or The car interior is clean with stress.

For a learner, the original order is the safest and most natural.

Not in standard Greek.

For the interior of the car, το εσωτερικό του αυτοκινήτου is the correct and natural expression.

μέσα usually means:

• inside
• in
• indoors

It is not normally used as a noun in the same way here.

So if you want to refer to the car's inside as a noun, use το εσωτερικό.

A simple pronunciation guide is:

To esoterikó tou aftokinítou íne katharó.

A few helpful notes:

• το = to
• εσωτερικό = e-so-te-ri-KO
• του = too
• αυτοκινήτου = af-to-ki-NI-too
• είναι = usually pronounced roughly EE-ne
• καθαρό = ka-tha-RO

The stressed syllables are:

• εσωτερικό
• αυτοκινήτου
• είναι
• καθαρό

Because in Greek, possessive relationships of the type the X of the car are commonly formed as:

• the noun + genitive phrase

So:

• το εσωτερικό = the interior
• του αυτοκινήτου = of the car

Together:

• το εσωτερικό του αυτοκινήτου

This is the normal Greek structure for phrases like:

• η πόρτα του σπιτιού = the door of the house
• το χρώμα του τοίχου = the color of the wall

Usually το εσωτερικό του αυτοκινήτου refers to the interior of the car, especially the inside space, cabin, seats, dashboard area, and so on.

In everyday usage, it is the natural phrase for the car's inside as a whole. If someone is talking specifically about one part, Greek would usually name that part directly, such as:

• τα καθίσματα = the seats
• το ταμπλό = the dashboard

So το εσωτερικό is a general term for the inside area.