Travelers spend hours scouring websites for savings on airfares and hotel rooms but often overlook ways to cut costs on parking fees at airports.
But if you know where to look, you can often find deep discounts, free parking and, in some cities, even get paid for parking your car at or near the airport.
Private parking lots with airport shuttle services ring just about every airport but can differ in price, security, convenience and added perks provided.
Discount coupons for airport parking lots also can be found online, in newspapers and travel magazines, on Groupon-type sites and through membership clubs such as AAA, AARP and Costco.
Many lots will offer discounts for reserving, and in some cases, paying for your parking spot ahead of time. But even if you're only shopping by cost, be sure the lot you choose is well-lit, secure and offers 24-hour on-call shuttle service to and from the airport because you never know when a scheduled afternoon flight arrival will end up delayed until 2 a.m.
Some off-airport parking lots compete by offering extra services, such as complimentary jump starts and tire change or inflation. Others, such as The Parking Spot, with lots near more than 20 major airports, offer customers free newspapers, bottled water and valet service.
Many off-airport lots also have frequent parker programs that offer everything from preferential spots and fast check-out to free days after a set number of paid ones.
Beyond traditional off-airport lots, many hotels near airports offer stay-n-park deals which can be both economical and convenient for early morning departures. Other options include driveway-sharing apps, such as JustPark and ParkingPanda, and peer-to-peer car-sharing services such as FlightCar and RelayRides, which let you park your car for free near an airport in exchange for making your car available for rent to another driver while you're out of town. If your car is rented out, these companies will also give you a cut of the fee.
Revenue from parking fees plays an important part in airport operating budgets.
Airports reported making approximately $3.1 billion, or 41.2 percent of their non-aeronautical revenue, from parking and ground transportation fees, according to the most recent concessions survey conducted by Airports Council International–North America.
So while the price to park closest to the airline terminal is generally higher than at off-airport lots, many airports offer discount coupons, frequent parker programs and other perks in an effort to stay competitive.
Weekly parking rates in the garage at Seattle-Tacoma International Airport, for example, are currently $130. But a quick search of the airport's website brings up a coupon for a full week of parking, including taxes and fees, for just $99.
Phoenix Sky Harbor International Airport, which earned $78 million from parking fees in 2013, offers early bag check-in for those parking in its East Economy parking facilities and discounts for prepaid parking reservations.
At Nashville International Airport, where parking fees represented 34 percent of the airport's fiscal 2013 operating revenues, the frequent parker program offers fast access in an out of a reserved section and free parking days for earned points.
Sometimes what you drive or where you're going can make a difference.
Long Beach Airport, for example, offers free parking for electric vehicles and throws in a free car wash for travelers who pay the $24 daily fee for valet parking.
Parking is always free at some smaller airports such as Chicago Rockford International Airport and Peoria International Airport and a promotion currently underway at Pittsburgh International Airport offers up to seven days of free parking for travelers flying non-stop on JetBlue or SouthwestAirlines to Ft. Lauderdale between Nov. 1, 2014 and Jan. 31, 2015.
—By Harriet Baskas, special to CNBC.com. Baskas is the author of seven books, including "Hidden Treasures: What Museums Can't or Won't Show You," and the Stuck at the Airport blog. Follow her on Twitter at @hbaskas. Follow Road Warrior at @CNBCtravel.