4.5 days for 4000kms. Sad state of European rail.

Your average work migrant does 2000km in a day with a Golf TDI and a tray of energy drink. One fuel stop. I’ve seen plenty of Romanians and Bulgarians do this. Turks and Moroccans are also known for their long drives.

To give some useful advice. You can shave off some time by using busses here and there. Helsinki to Lisbon with FlixBus is 75 hours.