Renting cars for your travel expeditions is always a frustrating process. Not only are some of their fees hidden in the fine print, but each rental car agency comes with its own set of rules. If you use the same rental car agency, then you might be in tune with their terms and conditions. But for those who travel less frequently, remember each agency's individual rules can be hard to keep up with.

Some of these stipulations are commonplace: return the rental car in its original condition, no smoking, and make sure your rental is covered by insurance. Others, however, have incorporated strange rules that most renters would not have even thought of (which is why it's important to read the fine print). Here are the 10 weirdest rules rental cars have that you never knew existed.

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10 You Have To Be 25 Years Old

This rule has always been somewhat of a myth. However, there is some truth behind it. While some rental car agencies don't have age requirements, almost all of them do have age restrictions. The general rule of thumb is that anyone under the age of 25 years old is subject to additional charges. This is especially true for those under 21. These fees are set up to protect rental agencies against inexperienced drivers, who are more likely to sustain damages to their vehicles.

9 A Child Seat and a GPS Costs Extra

Anything extra that a renter may need for a vehicle is going to cost extra. Even necessities such as car seats are liable to pay a "seatbelt fee" in lieu of bringing your own. Those who require GPS devices inside their rental will more than likely be subject to higher initial costs. An easy way to avoid these fees is to simply bring your own. The price of a rental car seat or a GPS can sometimes be higher than what you will pay for these items at a local store.

8 There Are Airport Drop Off Fees

Airport rental agencies are notoriously more expensive than outside vendors, even if they're from the same company. In addition, if you decide to get your rental from a local dealership, but opt to drop your car off at its sister location at the airport, you will be charged a fee. Enterprise in particular notes that, "If you drop off your rental vehicle at the airport but did not originally pick up your vehicle at the airport, an additional drop fee may be charged."

7 Customers Pay Extra For Driving Less

You would never think that putting fewer miles on a rental car would be a penalty, but that's actually the case for most rental agencies. Budget says that, "if you drive less than 75 miles, an automatic USD $15.99 ($16.99 if you rent the vehicle in California) EZFuel service charge will be applied."

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Their EZFuel program is in place for those who may not have time to fill up the car's tank before returning it, though these rates are dramatically higher than the average tank of gas. This less than 75-mile rule also suggests that the charge can be removed with proof of gas purchase.

6 Customers Always Pay For Gas

No matter if you choose a rental car agency's EZPay service or not, you will have to pay for the gas as a customer. If you decide not to prepay for gas, but return the car on empty, a per-mile or per-gallon charge will be found on your bill later on. Or you can simply decide to indulge in their EZPay system or fill up the tank yourself. Whichever way you choose it, you as the customer will be paying for a full tank of gas for a rental car, not including the amount you spend while using the vehicle.

5 They Don't Charge Cancelation Fees

This is a positive upside to rental cars' strange rules. Unlike airlines and hotels, rental car companies don't charge cancelation fees. This makes it easier to shop around for prices months in advance to ensure that you're getting the best deal. You can set up five different rentals for your vacation as you see the prices drop and cancel the previous one with no repercussions. Keep in mind, there will be a fee charged to your card as a hold, but this is dropped once the rental is canceled.

4 They Can Reclassify Car Sizes

This is a tact that has been done by agencies such as Alamo. Back when they were purchased by Enterprise, Alamo reclassified their cars. This may not seem like a big deal until you realize that what is normally classified as a compact car is considered a midsize. by the rental agency.

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These car class upgrades are an easy way to sneak in extra fees, so be sure to check what your rental car is listed as.

3 Return Policies Vary

Return policies will vary depending on the rental car company, which can be frustrating if you don't travel often. Most rental car companies want to ensure that their cars are returned in a timely manner for their awaiting customers. Understandably, this means that they want their cars returned at the exact hour. However, recently some places such as Enterprise are allowing a one hour grace period, which means that renters can return the car within the designated return time with no extra fees.

2 Driving With Pets May Cost More

While you most definitely need to double check with your rental car company's pet policies, you should also read their cleaning fees carefully. Even if the rental is designated as "pet-friendly" you may be subject to cleaning fees. Budget reasons that if you return the car in clean condition but there is an excessive amount of shed pet hair or soiled seats, you will be responsible for the cleaning services that will be needed in order to rent the car out again.

1 They Charge For Early Returns

When you sign a rental car agreement, the contract is biased to stick to the allotted rental time and initial stipulations. If you break that contract, even if it means returning the car early, you will be charged extra fees. This is especially true if you received the car as a weekend rental, but return the car before Sunday. In this case, the weekend discount no longer applies, so the base fee will be altered. Car rentals usually have a lower rate the longer you rent it out, so if you six-day rental turns out to be a four-day rental, expect your initial pricing to change.

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