Because they cost so much for companies to buy and maintain, renting a car can be a dicey little game. Car rental companies, like every other business on the planet, are in the game to make money and, as a result, will try to pass on costs to the consumer -- especially when they are expensive costs like car repairs.

In a recent post from The Consumerist, a man only known as Dan and his wife recounted their car rental experience with Budget on a trip to Hawaii, which served as some very clear evidence of this fact as well as a reminder of how documenting your rental car via photos and video can save you a lot of money.

While waiting for their "econobox" to be prepped at the Budget location in Oahu, Dan explained in the post, they were offered an upgrade to a Dodge Challenger for free instead of waiting for the other car. The deal seemed like a no-brainer and they took it. Unfortunately, when the car was delivered, they discovered it was "trashed."

"Dents, dings, scrapes and the front fairing was hanging loose. I photographed everything and noted it on the forms being very specific. The attendant signed off on everything, I got my keys and we spent a week on the lovely island," Dan said.

"[Then,] when we turned the car in, the receiving attendant gave the car very careful scrutiny and took our damage form copy when we rented it, signed off on the car and we flew home. No worries."

Everything seemed to be fine and dandy until two weeks later when Dan received a phone call from Budget asking for details about the accident he had been involved in. Confused and knowing that he didn't get in an accident while in the car, he contacted Budget's investigations department and told them he had pictures and video of the car's pre-existing damage.

Only after he explained his careful documentation and the fact that he had pictures did Budget miraculously "find" his existing damage claim.

The moral of the story, Dan said, is to "photograph your evidence and maybe photocopy/scan and save all your paperwork...you never really know what's going to pop out of the woodwork to try and bite you."

Pain-free car rental

Unfortunately, stories like this are more common than we would like. Because of this, follow these tips to ensure that you don't get hosed and end up spending much more money on your rental than you anticipated.

1. Pre-book when renting a car

All the travel agents and car-rental experts we spoke to were unanimous in one thing: If you expect to show up at the airport without a pre-booked rental and get a good deal on your car, you can think again. This is especially true during busy times like weekends and holidays, when you'll likely be in for a long wait in line as well.

"There's tremendous advantage to booking in advance, you can do comparison shopping, go to different travel sites and individual rental sites and shop around for the best deal," says Rike Wedding, of Car Rental Express.

If you're really stuck, it's often worth checking out off-site car rental locations if it's possible to get to them from the airport. Many off-site rental firms can be reached by an airport shuttle or train connection in major metropolitan areas. Often a quick phone call to check availability is all you need, and prices are usually cheaper than on-airport operators.

2. Check insurance overlaps

Amid the extraordinary minutiae involved in car-rental insurance, it's important to note that some drivers will already be covered by their own auto or household insurance for many of the insurance packages a rental company will try to get you to pay for. The simple solution is to check with your own insurance company before setting foot in the car rental office. This can often mean saving between $7 and $12 a day on renting a car.

While you may be covered by your own auto policy, the value of your rental may eclipse that of your personal vehicle, so make sure that you're covered for a higher-priced vehicle if that's the case. (Yet another reason to book in advance.) One benefit of buying insurance from the rental company is that any claim will not appear on your own auto insurance, therefore "clean-driver" or "no-claims" policy benefits will be unaffected.

"The rental company will always offer you insurance and it's your decision as to whether you'd like to take it," says Marie Montgomery at AAA. "It's probably not worth it for a lot of people who think they have enough coverage, but it's a good idea in some situations to have some basic liability coverage of their own. [It's] always a good idea to read the fine print."

3. Cameras aren't just for vacation snaps

A good rule of thumb -- and particularly if using a smaller, off-brand car rental agency -- is to take pictures of the vehicle before you drive off the lot. This, of course, means that a thorough inspection of a prospective rental vehicle must be undertaken.

Even the smallest imperfection should be documented. Check wheel rims, bumpers and fenders. Look for small dings on doors or cracks in glass. Also check the interior thoroughly, looking for spills or tears on seats or floormats. Snap photos of everything and review them on your digital camera to make sure you can clearly see the preexisting damage. This can help diffuse a fraudulent claim of damage -- or an honest mistake -- by the rental car company.

Blake Fleetwood, spokesman for the American Society of Travel Agents, says some companies will be looking to get any cash they can in a tight economy. "Car companies have been hurting like airlines and hotels so they're looking for extra charges to stick onto people," he said. "Damage recovery has become a key profit center for auto companies."

4. Don't buy gas from the rental company

Gas prices, in our opinion, are high enough. But many car rental places fill up a car with gas before a consumer drives away on the proviso that a driver will return the vehicle with a full tank, or the company will fill the tank and bill the driver later. This is where consumers can get fleeced on gas markups often approaching 100 percent. Make sure to leave yourself enough time to fill up before returning the vehicle. And beware as well, of those gas stations near the airport that up their prices to take advantage of car rental customers desperate to make their flights.

"Always make sure you gas up before you return the car, they can really hose you on gas charges. Sometimes [you'll pay] five dollars or six dollars instead of three dollars," Fleetwood says.

5. Get group benefits

Going through a travel association or car club often gets you a better deal on renting a car. Members of organizations or motoring clubs like the AARP or AAA can glean significant savings on rental rates, often between 10 and 15 percent. Costco shoppers also may benefit from tie-up deals. Scour newspapers or the Internet for discount coupons. Packaging your rental with your airline or hotel booking may also help cut costs a little, and most major travel web sites and travel agents offer some kind of package discount.

6. Get the facts on hidden fees or charges

Make sure before driving off the lot that all charges are accounted for. Ask at the counter that all potential charges be detailed up front. Most companies carry an incremental charge for picking up your car in one location and dropping it in another, generally between $35 and $50.

But some one-way rentals between popular in-state tourist destinations -- say between Miami and Orlando in Florida -- may not incur an additional charge. Note that many rental companies offer free mileage as part of a rental package but, again, check this before leaving the counter to avoid additional per-mile charges that can reach 40 cents or more.

7. Try smaller operators

While the larger companies typically offer more choice of vehicles at cheaper prices, at certain times of the year or in some locales it's good to check out some of the smaller independent rental companies. Smaller companies also can offer a more personalized service and more flexibility.

Wedding, whose agency represents more than 300 smaller operators, says, "If you need a car for another couple of hours beyond the official end of the day, you could probably negotiate something like that and the manager has the authority to say, 'Fine, you have a deal.' Small companies are interested in repeat business and a way to get it is to provide excellent customer service. They can't advertise the way the major chains can."

Remember, smaller companies add on hidden fees and charges just as frequently as bigger rental chains.

8. Use your cellphone to reserve a car

If you're not near a computer, you can use a cell or smartphone to make a reservation as more travel sites seek to capitalize on new technology to make the rental experience more convenient.

Wedding said, "We're headed toward making things easier for mobile phone users. [Alongside reserving your vehicle] if you have an agency number in your smartphone you can call from the airport make sure you have shuttle information. Our software runs 100 independent agency web sites. We're going mobile-friendly for convenience."

9. Upgrades are common but not automatic

Hiring a mid-range or compact car and expecting an upgrade to a larger or more loaded model is a common strategy among consumers, but it doesn't always lead to the expected results. Around holidays, you can pretty much forget about an upgrade, but much will depend on individual circumstances. In some cases, consumers will even get downgraded to a cheaper vehicle, though without having to pay the more expensive rate.

"It's a 50-50 situation, it really depends on the establishments. If there's more demand for medium-priced and cheaper cars there will be upgrade. But if you go skiing in Aspen, those Suburbans are going to be highly sought after. Even if you've booked a four-wheel-drive you may get downgraded," Fleetwood says.

"Try to book in advance. One trick is, if you can't find anything available, make reservations for a couple days earlier then cancel, say you can't make it and sometimes cars open up. I wouldn't always recommend it, but it's worked for me," she says.

10. You have recourse in any dispute

Getting hit by a surprise charge on a credit card after dropping off a vehicle is a major sore point. Our advice remains to leave yourself enough time to go over any charges before leaving the rental car premises. Many major chains will inspect the car there and then and present a bill for any damage incurred during the rental period, to alleviate the anxiety of a future credit card charge.

Still, some disputes will remain. Our experts told us to make sure that car companies provide evidence and justification for every charge they make before allowing them to charge your credit card. Make sure you personally inspect the vehicle with the rental-firm worker. If you've taken pictures of all damage before you drove the car off the lot, you should be in the clear.

In a lingering dispute, it's helpful to have booked through a major car chain or travel agent, who often staff whole departments to resolve such disputes. Similarly, taking out insurance through a major outlet can often grease the wheels of an unexpected claim.

Remember, as in all things, you get what you pay for.

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