As in the rest of the travel industry, car rental business is up and expected to continue to climb. The following ten tips, compiled by SmartMoney.com, can turn any traveler into a savvy renter.

1. Car rental companies are magnets for high city and state taxes: Renters can get around paying these taxes and fees by picking up their car away from the airport, where charges can be up to 45 percent lower.

2. GPS technology allows rental companies to track their cars: Some companies have installed GPS units in cars for navigation, but some have also been known to use the devices to charge renters for wear and tear if they drive out of state boundaries or go above the speed limit.

3. Rates change often, sometimes daily or even hourly: Car availability, a high volume of bookings or cancellations, or even reserving online versus at an airport desk can all result in fluctuating prices; it’s best to comparison shop and then check back later to see if prices have dropped.

4. You probably don’t need to pay for insurance when renting a car: Check with your regular auto insurance provider or your credit card to see if they already provide the required collision/damage waiver and liability.

5. A reservation doesn’t guarantee you’ll get the car you want: Because a reservation guarantees a class of car rather than a specific model and is contingent on availability, ask for a rate adjustment if you end up with a smaller car than what you reserved. If the lot is empty, the company is responsible for finding you a car elsewhere and covering the difference.

6. Companies bank on renters adding amenities at the checkout counter: Extras like GPS navigation systems, satellite radio, electronic toll payment, and upgrades to specialty cars are all pricey add-ons the company hopes you’ll splurge on.

7. Small, independent rental car companies usually charge less: Look for smaller companies on CarRentalExpress.com for rates that can be as much as $30 less per day than the larger agencies.

8. Many rental companies are cutting corners: Watch for fine print on rental contracts that impose stricter rules, for example, shortening the grace period for returning a car or making renters liable for damage caused by hurricanes, floods or other “acts of God.”

9. Try not to return a rental car with an empty gas tank: Rental companies will charge a fee for a car returned on empty; either prepay for a tank of gas at when you pick up the car or be sure to fill the tank before returning it.

10. Promotional rates can be hard to take advantage of: Car rental companies advertise great deals all the time but don’t be surprised when rules and restrictions buried in the fine print make it all but impossible to use them.