Renting a car seems simple enough, but most rental companies unnecessarily complicate the process. Whether you are visiting a new city, are heading out on a road trip or just need to pick up a ride for the day, car rentals can vary drastically, both by type of rental and by company. When making decisions about your rental, you'll have to choose the size and type of vehicle, a manual or automatic transmission, whether or not to get additional insurance and sometimes whether to get limited or unlimited mileage. Fortunately, with a little advance planning, that last option is easy to figure out.

Limited Miles vs. Unlimited Miles

Each car rental company has an individual policy when it comes to mileage limitations or mileage caps. These limitations are also affected by whether the driver is renting the car in a U.S. state or in a foreign country. Most major companies, such as Hertz and Enterprise, allow unlimited mileage car rental within a specific state when traveling domestically. Driving a car from one state to another usually incurs an additional fee per number of miles, so it's best to check into the specific rules ahead of time, especially when heading out on a cross-country journey.

Some companies apply mileage restrictions on weekends. Enterprise, for example, allows 100 miles per day for all weekend rentals, the restriction applies to any rental from an exotic car to “best car” suv to a standard economy car. Each additional mile is typically charged at a small fee, but those can add up quickly when the odometer is read and your debit or credit card is charged at drop off. Hertz charges $0.25 per extra mile, which means renters should be super careful to calculate the distance they plan to travel on the rental before signing the rental agreement.

With this in mind, always select unlimited miles if it's available. Those rentals don't tend to cost much more than a limited rental, and they often can be the same price. It will alleviate a lot of stress to not have to think about each leg of the journey and how much it's costing. If the rental car company doesn't offer unlimited miles initially on a booking, ask a customer service rep about it. It's always best to check what's possible.

When traveling a short distance, or if you only need the car to go back and forth across town, a limited mileage rental shouldn't be a problem. Keep track of how far you drive, and calculate all your driving plans in advance so you won't go over the limit and have to pay extra.

Traveling Outside the U.S.

There's no need to be nervous about driving in another country. When renting a car outside the United States, it's best to look at how far and where you plan to travel when selecting the type of rental. If you will be using the vehicle to hop around to various European countries, it makes sense to pick an unlimited mileage plan. Sixt Rent a Car, for instance, offers cars of all sizes and models, with unlimited kilometers for those planning to journey to several countries. Hertz also offers unlimited travel on most rentals within Europe.

If you'll be staying within a specific city or region, a limited mileage plan should suffice. Check to see how far you'll go on a mapping program such as Google Maps, and be sure it matches with the allotted miles. If you surpass the mileage limit, the rental company will typically charge a fee per additional mile (or kilometer). Doing research ahead of time and planning a route can help lessen those extra costs.

Other Considerations

Luxury cars.‌ Some car rental companies don't allow unlimited mileage plans on luxury vehicles, so it's best to research ahead when planning to book a premium car, like a Mercedes or Mustang. Call the rental company directly when unsure.

Frequent flyer discounts.‌ If you're concerned about pricey car rental costs, look for discounts and offers before booking. Most airline frequent flyer programs have discount codes for their customers, which can save up to 35 percent on a car booking. Check your preferred airline's website to find those codes.

Cost comparisons.‌ It also helps to do some research and compare costs and benefits. Find out which car rental companies include unlimited miles for all their rentals if that's what you need, and avoid any companies that charge too much for extra miles.

It might all sound complicated, but navigating the car rental process will probably be much easier than navigating the roads of a new city. Planning ahead is key, as is mapping out where you intend to drive. And ultimately, it's about what makes you feel most comfortable.