Don't Use a Debit Card- Many rental car locations will not allow you to use a debit card for a rental car or will place a large hold (usually $500-1,000, which could result in overdraft). Instead, use a credit card with rental car insurance.
Decline the Fuel Option- Rental car companies usually offer two fuel options (1) $7+ dollars a gallon if you forget to fill up the car or (2) a very reasonable rate but you pre-pay for the full tank of gas regardless of how much you use. Therefore, unless you are guaranteed to return the car with less than half a gallon of gas remaining, you are better off filling it up on your own before you drop it off.
Decline the Insurance Option- If you have your own collision auto insurance, you can decline the rental car insurance option. I always use a credit card with rental car insurance, which protects damage to the rental car, but not to other cars or property, so you still need liability insurance. Credit card rental car insurance is great because if you back into a concrete pole, your regular car insurance will never know and won't increase. If you are traveling in a foreign country, be sure to request a verification of coverage from your credit card provider to avoid a car rental place forcing you to buy insurance. (Exception: I always get insurance for Moving Trucks since they are generally not covered by your own insurance or credit card insurance).
Create a Loyalty Account- This will take a little time to set up, but it will save you a lot of time in the long run. With Hertz at the airport, I skip the line, look at the electronic board that displays a list of an alphabetical list of names with zones of my car (usually the President's Circle row), head to the row of cars, pick one, and head to the exit where they scan the car and verify my license and reservation. If you don't have an account, you could be waiting for 30+ minutes and you have to listen to them upsell you all of the fuel options, insurance, etc. (you can decline all of these in your profile).
Inspect the Car- Make sure you thoroughly inspect the car inside and out before you drive off the lot. You do not want to be charged for damage that you did not cause. If there is some damage to the car, even a large scratch, be sure to have the employee indicate that on the "car condition form" when you check out.
Underage Driver- Rental car companies will charge an underage fee if you are under 25 years old. On average, it is an extra $25 per day, but below are some ways to avoid that fee.
- USAA- If you book using USAA, you can waive the underage fee for 18 to 24-year-olds for Avis, Budget, and Hertz. For Enterprise, you need to be between 21 and 24 for the fee to be waived.
- AAA- If you book using AAA, you can waive the underage fee for 20 to 24-year-olds at Hertz.
- SilverCar- You can rent from SilverCar without an extra fee if you are 22 years or older.
Returning the Car Late- Many car companies offer you a 30-minute grace period from your scheduled return time, but if you go over that, you could be facing paying for an extra day (at a usually higher rate). The only exception is to this rule is using the American Express Platinum code for Hertz, which allows for a 4-hour grace period.
AutoSlash- AutoSlash is a great website to start finding quotes for rental cars or have them track to see if a cheaper car rental becomes available. They find you discounts based on different programs or credit cards you may have (see below). However, it does take up to 30 minutes to get a quote, but usually, the email from them arrives in less than 10 minutes (I typically start searching rates from the next three paragraphs in the meantime).
Hotwire and RentalCars.com- I typically also check both of these websites just in case they have a cheaper rate than AutoSlash.
Costco and AAA- If you have either a Costco or AAA membership, you can get fairly significant discounts. AAA only works with Hertz, but Costco works with Budget, Avis, Alamo, and Enterprise. (Despite AutoSlash searching the AAA and Costco rates, I have found that sometimes it's cheaper if I search the code myself)
Other Discounts- The American Express Platinum offers discounts at Hertz (211762; also 4-hour return grace period), Avis (A756900), and National (5028695). You can also search around the car rental companies own website for discounts (e.g., Hertz) or promotional codes from your favorite airline or hotel loyalty programs (e.g., United's rental car page). Additionally, if you search around you can find promotional codes from your college's alumni program, professional associations, or even your corporation (or if you want to risk it, pretending to be associated with that corporation).
Renting from Non-Airport Locations- There can be a large cost savings by renting from a non-airport location since you don't have to pay many of the taxes and fees that are associated with airport rentals (cities try to their best to tax business or leisure travelers rather than their own citizens). I generally find that non-airport locations are generally (1) understaffed (sometimes one employee doing the job of several); (2) the cars are older and not as nice (less of a big deal if you don't have elite status. For example with my elite status, I can usually get a $35,000+ car with low miles at the airport vs. a $25,000 car with 25k+ miles at a non-airport location); (3) most of the locations are franchises, so your service may vary; (4) they are more likely to run out of cars (since they only have a limited number to start with); and (5) they have limited hours (usually 8 am to 6 pm on weekdays, and closed (or extremely limited hours) on the weekend).
Small vs. Large Rental Car Companies- Many times companies such as Dollar, Fox, Sixt, and Payless, will be cheaper than Hertz or National. Those companies can usually offer cheaper rentals since they (1) have less customer service agents; (2) located further from the airport; (3) may charge hidden fees (such as tolls below); (4) don't have a full-scale loyalty program (you can earn points, but no elite perks or fast-track rental process). One time, I was renting at the Phoenix Airport and one of the smaller rental car companies had a line of at least 150 people serviced by 3 overworked customer service representatives (probably a 2-3 hour wait; Luckily, I was in and out in 5 minutes with Hertz). I personally stick with Hertz or National, but if there was a huge difference in price, I would rent only if the company offer an skip the line/express check-out option (e.g., Fox's "FOXPress" mobile app, but that only offers express check-out at a limited number of airports). The exception to the rule is SilverCar, which is a small company and usually a more expensive option, but you get to drive Audis and their customer service is great.
Cashback Websites- You can also typically get 2-6% cashback on most car rentals by clicking through a cashback portal before you book such as Ebates, Giving Assistant, TopCashBack, and Simply Best Coupons. (You can also see a comparison of the rates on CashBackMonitor). However, for some websites, you can not earn cashback if you use a corporate or promotional rate.
Rental car companies make a large amount of money by charging customers a fee to use their toll transponder/E-ZPass. Companies will either charge (1) flat rate per rental day to rent the transponder in addition to the cost of tolls; (2) convenience fee for any day you use the cashless toll (e.g., if you pay a $5 toll, you also get charged a $2.99 convenience fee for that day); (3) flat rate that includes all tolls; or (4) the cost of the toll only without any additional fees.
Alamo/Enterprise/National- All three companies are owned by the same company and have identical toll charges and they also offer a great deal of disclosure of their toll policies. These companies charge $3.95 per usage day for the "Video Tolling" state and $3.95 per rental day for "Transponder" states (Map detailing each state). Additionally, the maximum you will be charged for that convenience is $19.75 per rental period. You can also find more information on specific regions.
Avis/Budget- $3.95 per rental day with a maximum fee of $19.75.
Dollar- Dollar offers an all-inclusive toll system, which allows you to go through as many tolls as you want. The cost varies by region, which usually means it will be very expensive. You can opt out, but if you go through a toll using their system, you will be charged the toll plus $15 per toll with a maximum of $105. Since some states only offer electronic tolls, it can be extremely expensive if you opt out and go through several tolls.
Fox- Dollar offers an all-inclusive toll system, which allows you to go through as many tolls as you want. It costs $8.99 per rental day in Florida (max of $134.85) and $11.49 in "Northern California (Bay Area bridges only), Colorado, Texas, Washington" with a maximum of 15 rental days or $172.35. For other states, you will need your own transponder. You can opt out, but you will be charged the toll plus $15 fee for each toll for a maximum of $90 in additional fees. Luckily, you can opt back when you return the car (just do it before the rental agreement has closed)
Hertz- $4.95 fee per day with no monthly maximum. (FAQs)
Payless- $2.95 fee per rental day with a maximum fee of $14.95 (Full Details)
Silvercar- No Fee. Only pay the cost of the tolls.
Sixt- Cost for all-inclusive toll option varies by state or you can pay the toll plus $5 for each time.
Thrifty- Cost for all-inclusive toll option varies by state or you can pay the toll plus $15 for each time (maximum of $90 per rental period).
Advice- If you don't want to pay these fees you have a few options: (1) avoid tolls using the settings function in Google Maps (but it will likely take you longer to get to your destination, which uses more gas); (2) carry cash and coins since some tolls require exact change; or (3) bring your own transponder (this will work in Northeast and Florida, but some places charge based on your license plate)