Car Rental Tips in the USA 
When you rent a car in the USA, there's more to consider than driving on the "other" side of the road. From international driving permits to liability insurance, renting a car in a foreign country can be a bit more complicated than renting one stateside. Here are some tips for getting a great deal, making sure you have the right documentation and driving safely while abroad.

Booking Your Car
Book in advance. Rental rates are almost always higher at the counter than they will be over the phone, even just 24 hours before pickup. If you have time, comparison shop. Visit the Web sites of several rental agencies and search for identical cars on your travel dates.

Whenever possible, make all car rental arrangements, from booking to payment, before you enter the United States. Doing it this way generally makes the process cheaper, easier, safer and less likely to include hidden clauses. Once you are overseas, shifting exchange rates, unfamiliar rental specs, language barriers and other cultural differences can cause unexpected problems.

Ask about weekend specials, late penalties and gas charges. Many hidden discounts or car rental hidden costs will not be explained at the time of rental, and it may be too late once you find out.

Ask what time a car is expected for drop-off. Many rental agencies begin charging for each 24-hour-period from the time of rental, and will bill a full day for cars returned after another 24-hour period begins.

Be aware that many companies have a minimum and maximum age for renters. Drivers under the age of 25 or over the age of 70 may face surcharges or not be permitted to rent at all.

Whenever possible, if you see an ad for a rental car special rate, clip the ad or write down the promotional code. Many of the best rates do not show up on agents' computer screens without a little prompting.

Always ask about senior citizen, AAA, credit card and frequent flier program discounts or add-on offers.

When making reservations for car rental pickups at an airport, choose a smaller car than you would typically desire. Airport fleets are often stocked with larger cars, as they are primarily used by business travelers, and you will often receive a free upgrade from a subcompact booking. Be aware, however, that European cars tend to be smaller than their American counterparts; while this might be useful if you're planning on driving on narrow country roads, it's not so great for those who are extra-tall, carrying a lot of luggage, or traveling with a family or large group. In these cases, don't take a risk -- be sure to order the size you need just in case you don't get an upgrade.

One of the most common extra charges is for insurance, usually referred to by rental companies as collision damage or Loss Damage Waiver (LDW). For an extra $10 - $25 a day, you can avoid liability for any damage to the vehicle, provided you're not found guilty of gross negligence. Insurance is optional in most states, although in a few states it is compulsory and built into the basic car rental cost.

Before you purchase the extra insurance, check to see if your regular car insurance covers you in a rental car. Most policies do. Some credit cards also provide insurance; check with your company to find out. Other optional insurance coverages include Personal Accident Insurance (PAI), Personal Effects Coverage (PEC) and Additional Liability Insurance (ALI), which you can purchase from the rental company. Again, your best bet is to check your existing policy to see whether you're comfortable with the coverage you already have.

Drop-Off Charges
An extra fee is usually charged if a car is returned to a different location than where it was picked up. This fee varies by location; in some instances there is no charge, while you could pay $1,000 or more for cross-country drop-offs. However, some companies do not require a charge when dropping off in-state at many Florida and California locations. 

The 24-Hour Clock
Be aware of the 24-hour clock rate. If you rent your car on Wednesday and return it on Thursday, most companies charge you one day only if you return it within 24 hours. Some companies will give you a 59-minute grace period before hourly charges start kicking in; after 27 to 28 hours you'll then be charged for the full extra day.

Early Return Fees
You might imagine that returning your car a day or two early would be a good thing for your car rental company, but unfortunately you'll most likely be dinged for that too. Many car rental companies will charge you $10 - $15 per day for early returns, but that's not all -- you may also have to pay a hefty rate difference as well, particularly if your shortened rental period means you no longer qualify for a weekly rate. At that point you'll be charged the default daily rate, which could cost you hundreds.

Most major rental car companies allow for unlimited mileage in the same state, but it's a good idea to check their policy before you reserve a car. Many smaller, local companies charge mileage if you exceed a given daily allotment. Another caveat: Some "special" rates may not include unlimited mileage, so be sure to read the fine print.

License Fees
Some states allow car rental companies to charge extra to recover the costs of licensing their cars, usually between 3 and 8 percent of the cost of the rental. You may not be told about this fee in advance, so make sure to ask.

Varying Rates and Peak Season Surcharges
Rental car companies' rates vary a great deal from city to city, and sometimes even within the same city. Make sure to shop around. Be aware that you may pay a specific surcharge for traveling at a "peak" time.

Age Penalties
If you're under 25, you may have to pay an additional fee, usually about $25 per day. Those companies who will rent to drivers under 21 often charge much steeper surcharges. Internationally, you'll not only see penalties for underage drivers but also for older ones -- those over 70 may have to pay extra (if they're able to rent at all).

Additional Drivers
Adding more than one driver to your rental agreement often carries a surcharge, anywhere between $7 and $25 per day. Note that some companies, like Avis and Budget, will allow the renter's spouse or life partner to drive the vehicle for no extra charge -- so if both partners are planning to take the wheel, consider renting from one of these providers.

Frequent Flier Fees
Car rental companies often charge a small fee when you request frequent flier miles for your rental. The fee varies by airline, and can range anywhere from a few cents to $2 a day.

There may also be additional charges for things you had not considered, like infant and child seat rentals, roof racks and other extras. These could run you anywhere from $5 to $25 or more per day, depending on where you rent.

International Driving Permits
Beware of phony IDP's! Only two agencies in the U.S. are authorized to issue IDP's: the American Automobile Association and the American Automobile Touring Alliance. Hundreds of Web sites sell fakes, many charging over $100, believe it or not. For more information or to locate the AAA nearest you, go to the official AAA Web site.

Be sure to get your IDP before leaving home, as it must be issued in your home country. An IDP is not a license itself, merely a translation of the license issued in your country of residence. If you are stopped by law enforcement officials abroad, you must present both your IDP and your U.S. license. The only driving record you have, therefore, is within the United States, so obey the local driving rules! Any infraction or citation issued abroad will be waiting for you when you return home.

Check with the consulate or embassy of the country you're visiting to find out their policies on international drivers.

Know Before You Go
Make sure you have a realistic idea of how much you'll pay to fuel your car in the country you're visiting. Generally, drivers in the U.S. pay less at the pump than drivers in most other nations. Leave plenty of room in your budget for gas expenses.

Familiarize yourself with the local rules of the road well before you actually get into the car. Study up on such details as which side of the road to drive on, who has the right of way in a traffic circle and whether you're permitted to turn right on a red light. The best sources for this type of information are the country's consulate or embassy, or an up-to-date guidebook.

Check with your auto insurance company to see whether a rental car abroad would be covered under your current policy. Unless you're renting in Canada or Mexico, you probably won't be covered under your existing policy, so you'll need to purchase insurance from your rental car company at the time of booking. Be sure that your coverage, whatever the source, meets the foreign country's minimum coverage requirements.

Don't forget your map! Particularly if you're planning on driving extensively, the security of having a detailed road map or atlas is more than worth the price you'll pay for it. If you own a GPS, you can usually download international maps (for a fee) on your GPS provider Web site.

Most car rental companies offer GPS rentals, so check the GPS rental rates for your rental car before you purchase an international map from your GPS provider. Rates to rent a GPS are charged per day or per week; for a two-day car rental, you will be better off renting a GPS and paying than paying upwards of $100 for an international map download for the GPS you already own.