General conditions

Age limit

All car rental companies have an age limit, usually 25 years. Some companies do however rent cars to younger people (21) for a little extra pay.

Other drivers

If more than one person is going to drive the car, this usually has to be stated in the contract. Ask the car rental company :

Who else can drive the car?
What terms and conditions are there?
What potential extra costs are there?

If you do not tell that there will be additional drivers, and the car rental company finds out, there will be issues with the insurance. The "illegal" driver may also be arrested by the police in some countries, because he or she do not have the right to drive the car.

Return

You do not necessarily have to return the car to the same place where you hired it. Sometimes you can deliver the car to other parts of the country, and sometimes in another country. Ask about this when you pick up the car. It may cost more to have a different delivery place, so ask about this. Many firms also offers this service for free, especially if both the pick up and the delivery are on two popular destinations (airport, and the city centrum)

Payment

Some firms only accept credit cards and not regular bankcards. Over the Internet you usually pay a small deposit with a credit card, and the rest when you pick up the car.

These are only general guidelines for different car types. Different car companies may have other standards than those indicated.