Instead of leaving your car to the airport you can choose a cheaper solution of having a company pick-up your car and store it to their parking. Upon your return to the airport the company will pick you up and drive you to your car. Such companies are: 

• www.park2fly.gr
• www.athensskypark.gr
• www.airtravelparking.gr
• www.usaveparking.gr
• www.xtrimairportparking.gr
• www.airpark.gr
• www.aetoiparking.gr