The exterior of a Costco as seen through a crowded parking lot

Costco charges an annual membership fee. Image source: Costco.

Costco (NASDAQ:COST) makes its money -- at least most of it -- whether its members shop at its warehouses or not. The retailer earns about 75% of its profits from membership fees.

That doesn't mean Costco doesn't want members to shop at its stores: It certainly grows its profits and its customer loyalty when consumers come in more often. Still, even though there are deals to be had, many of the warehouse club's members don't take full advantage of what paying the annual fee brings them.

Below are seven ways you can get more out of your Costco membership that you may not have considered. Of course, not every way works for every member, but even if you only use a few, you should be able to dramatically increase the value of your membership.

A gas pump

Costco's gas can be dramatically cheaper than the gas sold at traditional stations. Image source: Getty Images.

Buy gas

It's not always true, but in general, Costco has cheaper gas than other local stations. Not every warehouse offers gas pumps, but those that do require you to first swipe your membership card, then enter a credit card to fill up.

The savings can vary, but most of the time, you will save anywhere from a few cents to $0.15 per gallon over buying gas at traditional gas stations. That's not worth it if Costco is out of the way, but if it's near your home, or you were visiting the warehouse anyway -- fill up, and add some extra savings.

A warehouse with its shelves packed with goods

Costco offers two types of membership. Image source: Getty Images.

Become an executive member

Costco offers two classes of membership. Its Gold Star deal costs $60 a year and gets you into its warehouses. The second tier, executive membership, costs twice as much at $120 a year, but it offers 2% cash back (up to $1,000 a year) on most items purchased at Costco.

Whether this makes sense for you depends on how much you shop at Costco. If you spent $100 a week at Costco (not unreasonable for someone grocery-shopping for a family) you would spend $5,200 a year at the chain and earn $104 back. That's not quite the cost of your membership, but it certainly underwrites what you pay to get in.

A couple relaxes in chairs on a beach

Costco offers deals on vacation packages. Image source: Getty Images.

Book travel

On its website, Costco offers a travel booking service. While you should compare prices before booking, the warehouse club offers very good deals on vacation packages. In general, the savings increase with items you add to your hotel and airfare, like rental cars and theme-park tickets.

In many cases, Costco also has good prices on rental cars. And, though offerings vary, the warehouse club can be a good way to arrange a trip to one of the major Florida theme parks at a price lower than booking direct.

A closeup view of credit cards

Costco actually offers one of the better rewards cards on the market. Image source: Getty Images.

Get the credit card

Costco members can double their cash back by getting the Costco Anywhere Visa from Citigroup. The card offers 4% cash back on gas (including at Costco), 3% on eligible travel and restaurant purchases, 2% back on any Costco purchase, and 1% cash back on all other purchases.

A man fits an elderly woman with a hearing aid.

Costco sells hearing aids for less than many of its rivals. Image source: Getty Images.

Get a hearing aid

Most Costco warehouses have a dedicated hearing-aid center. In these small stores-within-a-store, licensed technicians can check your hearing and fit you for a hearing aid if you need one. These are the same hearing aids sold under a variety of big brand names, at a fraction of the cost. A Costco member could save hundreds of dollars, or even as much as $1,000, compared to buying a similar hearing aid elsewhere.

And unlike many of its rivals, Costco does not pay its technicians a bonus based on sales. That removes any incentive they might have to upsell customers, or even to sell a hearing aid to someone who really doesn't need one.

A woman is seen driving a car.

Costco can help you get the best price on a new car. Image source: Getty Images.

Buy a car

Costco's auto program takes the haggling out of buying a car. The company selects, trains, and certifies dealers in each market to work with the program.

"We shop the competition to make certain our dealers remain competitive in their local market; based on the information we gather we help our dealers determine a prearranged price that represents a great value for Costco members," the warehouse club explained in an email. When a member visits the participating dealer, he or she can purchase the vehicle at that price "without the need to haggle."

Packs of brightly colored pills

Costco warehouses have pharmacies. Image source: Getty Images.

Fill a prescription

Even if you don't have insurance, Costco can save you money on many prescription drugs. The warehouse club doesn't offer specific savings across the board, but it promises members savings of "up to 80%," and it lists some pricing examples on its website. Again, this is an area where you should comparison-shop (and having insurance might change whether this is a value or not).

In many cases, especially on popular drugs, Costco will be cheaper than rival pharmacies -- simply because its drug program isn't about driving revenue, but is another way to keep members engaged.

Daniel B. Kline has no position in any of the stocks mentioned. His father in law works at Costco in the hearing aids department. The Motley Fool owns shares of and recommends Visa. The Motley Fool recommends Costco Wholesale. The Motley Fool has a disclosure policy.