Driving from Germany to Portugal

Hi All, 

I am planning to drive from Germany to Portugal in the coming months. Does anyone have experience of this especially how you managed the need for PCR tests to enter countries and the 48/72 hour window? If I take a test, wait 48 hours to get result before starting travel, by the time I have finished my first day's travel, my PCR test will be out of date???

Any advice would be really appreciated.

Thanks

Tony