If you choose to visit Kefalonia with your car, you have two choices.
You can drive from Athens to Kyllini, trip lasts about 3 and a half hours or Astakos in Aitoloakarnania. Kyllini and Astakos can be accessed via the Athens-Patras National Highway, if you are travelling from Peloponnese, Athens or east-central Greece.
If you are driving from northern Greece you need to take Egnatia Odos towards Igoumenitsa and then drive southwards. If you are driving through the Athens-Patras highway and you want to take the ferry from Astakos, you need to pass the bridge of Rio-Antirio and continue through Mesologgi towards Astakos.
Once you reach Kyllini or Astakos you take the ferry to Kefalonia.
There are daily departures from Athens to Kefalonia, from Kifissos Terminal Station in Athens. The bus will go from Athens to Kefalonia (through Kyllini ) and will reach its final destination, Argostoli, within about 6,5 hours.