Overseas

Many of the above charges, including airport fees, underage driver surcharges and local taxes, also apply to international rentals. Most travelers rely on credit cards to cover collision insurance overseas, as costs are significantly higher than they are in the States. But due to the high risks, some credit card companies now refuse to provide this coverage. Be sure to contact your credit card issuer before you leave to be sure you have coverage in the country you're visiting.

There are many country-specific fees and charges to keep an eye out for. For example, theft insurance is mandatory in Italy (at a cost of about $15 to $25 per day), and there are highway charges for cars driven in Austria or Switzerland; you'll need to purchase a sticker to avoid paying a fine.

If you don't have an international driving permit, you may also have to pay for a temporary permit, which can cost $10 to $20 or more. For more on international driving permits, see Renting a Car Abroad.