"Ezek autók."

Translation: These are cars.

[Casey4133]

Can this not be just 'these cars' also?

[gergo2]

No, that would be "ezek az autók".

[sgtwickool]

How do you say "these are the cars" then?

[gergo2]

The same way: "Ezek az autók."
The only difference is that this latter phrase is an entire sentence, while in the sense of "these cars" it is part of a larger sentence, e.g., "Ezek az autók pirosak."/"These cars are red." In practice it's clear from the context what is meant.

[AndrsBrny]

In addition, the sentence here means these are cars. So, to give you the full picture:

ezek az autók can be a phrase (without being a full sentence) meaning these cars.

Ezek az autók. can be a full sentence meaning These are the cars.

Ezek autók. can only be a full sentence meaning These are cars.

[killerman64]

how would you pluralize kocsi? kocsis?

[Alice53032]

Kocsik. Kocsis is a slang term for a chaffeur or a taxi driver