How to save more on your next car rental

Car rentals can be one of the most expensive parts of travel, next to booking the flight and the hotel. But it doesn't have to be that way.

Over the years, I've rented vehicles in over a dozen countries around the world. From those experiences, and a significant amount of research, I've learned some extremely useful tips that I use when renting a car. And to share the wealth, I'm passing them along to you, so that you can save big money on your next rental. Let's get started.

1. Deny the Insurance

Almost all major credit cards will cover your rental insurance, so if you're paying for the car on your credit card, there's almost always no reason to pay for insurance. (See also: Travel Perks You Didn't Know Your Credit Card Offers)

If you have put rentals on your credit card in the past, and still paid the rental agency for the Collision Damage Waiver (CDW), I'm sorry to be the one to tell you that you wasted your money. However, sometimes rental insurance specifics can be hard to understand or hidden in the small print.

You want to make sure that you have Primary Insurance Coverage with your credit card, meaning that if something were to happen to the car (knock on wood) while it's in your possession, you'll be able to file the claim directly with the credit card's insurance rather than fussing with the rental company's insurance plan — which most people want to avoid like the plague.

2. Earn Rewards Points With Your Rental

Some credit cards will give you some pretty lucrative points bonuses when you're renting a car. Make sure you check your current rewards programs on all of your cards and try to use one that offers a bonus for rentals. The CITI® Hilton HHonors™ Reserve Card from our partner Citi offers five bonus points on every dollar spent on car rentals and 25% off of rentals with National Car Rentals. The Chase Sapphire Preferred Card gives 20% off when you redeem points for car rentals.

3. Earn Points on Your Gas

You're going to have to pay for gas during the time you have the rental car, so why not earn some serious points at the pump? Use the credit card that offers the most rewards on gas purchases. The Blue Cash Preferred Card from American Expressoffers 3% cash back at U.S. gas stations (terms and limitations apply).

4. Book the Car With Your Flight

Next time you're booking a flight and you know you're going to want a rental car for a portion of your visit, consider clicking that "Flight+Car" tab that appears at the top of the page on your favorite booking engine. This little tab will open a whole category of secret discounts that can often save you money when you reserve a car with your airline ticket. (See also: 40+ Most Useful Travel Websites That Can Save You a Fortune)

I ran a test booking for a return flight from New York to London in November of 2015 with Expedia and found that when booking a Hertz rental with the flight, the car was only $160 for the week. When searching for the same car and the same dates on Hertz's website, it was $225 for the week. In this case, the Flight+Car hack saved $65 in a week.

Note: Savings vary depending on flights and dates, but there are times when you can nearly earn a free car rental by using the Flight+Car tab.

5. Rent Long-Term

The longer you rent your car, the cheaper it will become. In a sample reservation I made with Avis, I found that the daily rental rate was $34.10, while the monthly rate was only $11.60 per day, for a savings of $22.50 per day. If you rent the vehicle for 30 days, you'll save $675!

On top of this amazing discount, many rental companies will waive the "drop-off" fee if you choose to leave the car at a different location than the one you picked it up from. These fees can be as high as $50. Add this to the savings above and you've kept $725 in your pocket over the course of a month-long rental.

6. Don't Pick Up at the Airport

I know, it's easy and convenient to simply hop off of your plane and into the driver's seat of your new rental, but if you're really trying to save money, you wouldn't do this! In my test bookings, I found that there are "airport fees" attached to reservations at almost all rental providers. These fees ranged from $9–$30. This may not sound like a lot, but if you're only booking for a day or two, that can be a large percentage of your overall rental rate.

A taxi into town to rent a car at a different location may cost more than $30, but if you're taking public transport or having a friend meet you at the airport, you may want to consider driving a few miles away from the runway to save on that pesky airport fee.

7. Return the Car With a Full Tank

Rental companies hate when they have to fill up the gas tanks. In fact, they hate it so much that they'll charge you ridiculous rates for returning the car with less gas than you took it out with. Apparently car companies use super premium fuel, because if they have to fill up the car for you, you'll find a charge on your credit card that's more than double the normal price per gallon.

Most rental agencies will give you the car with a full tank. Make sure you return it with the same amount, or more.

8. Use a Promo Code

Rental agencies love to run promotions and discounts for fixed periods of time. While you're shopping for your next rental car, keep your eye out for a little box that says "promo code" or "discount code." After you've found the deal that best suits you, run a Google Search that looks like this: "your rental company" + "promo code." Dozens of sites will pop up that will give you codes that you can put into that magic box to save big money.

Another useful tip is to look on the rental agency's website for words like "Special Offers" or "Promotions" and click it. Sometimes there are some pretty hefty discounts hidden in these pages and if you book the right car at the right time, you can save a lot of money.

9. Don't Speed

I consider myself a pretty cautious driver, and I've managed to only get nailed for one speeding ticket during all of my time renting cars. Luckily, my ticket was in South Africa and I was able to pay the officer right there on the street — perhaps not "officially" but it did the trick.

Had the officer put the ticket into the system, I would've had to pay $175 for my ticket plus a $50 "administrative fee" with my rental company. Simply put, almost all rental agencies have these fees and they can quickly add up if you're a fast driver.

10. Be Elite and Get More Perks

As I mentioned earlier, you can earn some good points by booking your rental on your best rewards credit card, but you should also know about your chosen card's special perks.

If you're an elite card holder, you can skip line-ups at the office, get a free day after renting for four days, get up to 25% off of your rental, or get a free car class upgrade! Call your credit card provider and ask if it gives you elite status with any rental agencies, or if it comes with any extra perks for car rentals.

This article first appeared at Wise Bread.