Μας συμφέρει να πάμε με το τρένο, γιατί το ταξί είναι πιο ακριβό.

The verb συμφέρω means to be advantageous, to be worthwhile, or to be in someone’s interest. So μας συμφέρει means:

• it is better for us
• it is in our interest
• it makes more sense for us
• it is more economical for us

In this sentence, the idea is that going by train is the better choice for us, especially financially.

Μας is the weak object pronoun meaning us / to us / for us.

Greek uses συμφέρει with an object pronoun:

• μου συμφέρει = it suits me / it’s worth it for me
• σου συμφέρει = it suits you
• μας συμφέρει = it suits us

By contrast, εμείς means we and is a subject pronoun. That would not fit here.

So:

• μας συμφέρει = it is advantageous for us
• εμείς συμφέρουμε would mean something like we are advantageous/profitable, which is a different meaning.

Greek often uses συμφέρει in an impersonal way, like English it is worth it or it is better.

Literally, the structure is close to: It is advantageous to us that we go by train.

The thing that is advantageous is the whole action να πάμε με το τρένο. Because that whole clause behaves like a single idea, the verb appears in the third person singular: συμφέρει.

Modern Greek does not normally use an infinitive the way English does. Instead, Greek usually uses να + verb form.

So where English says:

• to go

Greek says:

• να πάμε

This construction is often called the subjunctive construction. After verbs and expressions like συμφέρει, Greek uses να + verb.

So:

• Μας συμφέρει να πάμε = It is better for us to go

This is about aspect, which is very important in Greek.

• να πάμε uses the aorist stem and presents the action as a single whole event: to go
• να πηγαίνουμε would suggest repeated, habitual, or ongoing action: to be going / to go regularly

In this sentence, we are talking about one decision or one trip, so να πάμε is the natural choice.

Greek commonly uses με + article + noun for means of transport:

• με το τρένο = by train
• με το λεωφορείο = by bus
• με το αμάξι = by car
• με το αεροπλάνο = by plane

So even though English often has no article in expressions like by train, Greek normally includes it.

Both τρένο and ταξί are neuter singular nouns, so they take the article το in the singular nominative and accusative.

Here:

• με το τρένο: after με, the noun is in the accusative
• το ταξί είναι πιο ακριβό: το ταξί is the subject, so it is nominative

Because neuter singular nominative and accusative look the same, you see το in both places.

Yes. Γιατί can mean both:

• because
• why

In this sentence, it means because:

• ..., γιατί το ταξί είναι πιο ακριβό.
• ..., because the taxi is more expensive.

When it means why, it usually appears in a question:

• Γιατί είσαι εδώ; = Why are you here?

So the meaning depends on the sentence structure and intonation.

Πιο means more, and ακριβό is the neuter singular form of ακριβός, meaning expensive.

So:

• πιο ακριβό = more expensive

Greek very often forms comparatives with:

• πιο + adjective

Examples:

• πιο καλός = better / nicer
• πιο γρήγορο = faster
• πιο ακριβό = more expensive

Because ταξί is neuter singular, the adjective must agree with it:

• το ταξί είναι πιο ακριβό

Yes. Both are possible.

• πιο ακριβό
• ακριβότερο

Both mean more expensive.

In everyday Greek, πιο + adjective is extremely common and often feels simpler and more neutral. So πιο ακριβό is very natural here.

Not completely. Greek word order is more flexible than English word order, because endings and articles help show grammatical relationships.

The original sentence is very natural: Μας συμφέρει να πάμε με το τρένο, γιατί το ταξί είναι πιο ακριβό.

But you could rearrange it for emphasis, for example:

• Γιατί το ταξί είναι πιο ακριβό, μας συμφέρει να πάμε με το τρένο.
• Το ταξί είναι πιο ακριβό, γι’ αυτό μας συμφέρει να πάμε με το τρένο.

The original version sounds like:

1. statement: it’s better for us to go by train
2. reason: because the taxi is more expensive

That is probably the most straightforward order.

Yes: ταξί is an indeclinable borrowed noun in Modern Greek. That means its basic form does not change the way many Greek nouns do.

So you get:

• το ταξί
• του ταξί
• τα ταξί

The article helps show its role in the sentence. In your example, το ταξί is the subject of είναι πιο ακριβό.

A fairly literal breakdown would be:

• Μας = to us / for us
• συμφέρει = is advantageous / is worth it
• να πάμε = to go
• με το τρένο = by train
• γιατί = because
• το ταξί = the taxi
• είναι πιο ακριβό = is more expensive

So very literally: It is advantageous for us to go by train, because the taxi is more expensive.

That is why a smooth English translation is something like: It’s better for us to go by train, because the taxi is more expensive.