1. Germany: 18 years (with an additional young driver's fee for drivers under 25)
2. France: 21 years (with an additional young driver's fee for drivers under 25)
3. Italy: 18 years (with an additional young driver's fee for drivers under 25)
4. Spain: 18 years (with an additional young driver's fee for drivers under 25)
5. United Kingdom: 21 years (with some car rental companies accepting drivers as young as 18)
6. Portugal: 18 years (with an additional young driver's fee for drivers under 25)
7. Netherlands: 21 years (with some car rental companies accepting drivers as young as 18)
8. Switzerland: 18 years (with an additional young driver's fee for drivers under 25)
It is important to note that these are general age requirements and specific requirements may vary based on the rental company, type of vehicle, and local regulations. It is recommend to check with your preferred rental company for specific details and any additional fees that may apply to young drivers.