Car rental agencies hit most renters on the gas charge. The agency charges a higher per gallon fee than most local stations. Make sure that you return the car with the same amount of gas in the tank as you received it. This way the rental agency cannot charge you more for gas. Check the rental agency's website. If you look under reservations, you will find that most charge a sales tax, vehicle license fee, and location fee. These items can add to the cost of your rental agreement.
Always decline to purchase the insurance the agency will offer you. This is a big money maker for the rental agency. You can provide your own insurance card as proof and in some cases your own insurance company will cover the costs of renting a car. Many agencies are trained to up-sell to the clients many items they normally do not need.
Look for travel coupon books or contact your local travel agent. AAA has offices all over the country and you can walk in and grab a copy of its free travel magazine. Inside the magazine are coupons for most everything --- hotels, food discounts, rental cars and more. If you are over 55 and a member of AARP, you could qualify for a discount. Visit the rental agency's own website and see what specials it currently offers. Try to rent the smallest car model in order to save money. The larger the car, the more expensive your daily charge will be. Research as many travel sites as possible. Many times they will offer deals on renting cars as a service they offer their clients.