Avoid rude rental car surprises

I'm usually a pretty savvy traveler, but a recent car rental mishap reminded me that even when you take every precaution, things still can go awry.

While planning a family vacation to Panama, I searched online for rental cars. One lower-cost rental car agency I'd never used before offered a significantly lower rate than the others. Ignoring the little voice in my head, I decided to try them.

Long story short: Although our flight was only one hour late, when I arrived bleary-eyed at the counter I was told that my car had already been given away – but I could upgrade to the next level for twice the price. After getting the runaround from the company's U.S.-based customer service department and learning that everyone else's rates had climbed equally high, I was basically stuck.

That experience taught me three lessons: A reservation isn't necessarily a guarantee; when traveling abroad, use trusted vendors – especially if it sounds too good to be true; and do better due diligence by researching travel columnists and message boards for rental tips, possible pitfalls and customer complaints.

Several car rental methods are available:

• Book directly from a rental agency (usually cheaper online than by phone).
• Comparison shop at websites like Priceline, Orbitz or Hotwire (although, I'll now be wary of buying a "blind" rental where you don't learn the carrier's name until after you pay).
• As part of a package including airfare and lodging.

I usually open several browser tabs to compare rentals side by side. Rates change constantly, so today's price may be much lower (or higher) than tomorrow's. Other tips:

• Book the best deal you can now and check back for lower rates.
• Incorporate additional fees and taxes into your comparison – sometimes they don't all show up until the "Total" page.
• Look for discount codes from membership organizations like AAA, AARP and airline frequent flyer programs.
• Consider picking up your car at a non-airport location where rates are usually – although not always – much lower.

Other decision-making factors include:

• Airport shuttle convenience.
• Fees for exceeding mileage allowances, alternate location return, late returns, or additional drivers.
• Fuel refilling charges – you may do better refilling the car yourself. Use a website/phone app like GasBuddy to find cheaper gas in the area.
• Surcharge for drivers under 25.

Rental agencies offer their own collision, liability, theft and other insurance coverage. Conventional wisdom says to avoid this route if your own insurance plans – or benefits available from your credit card – provide similar coverage. However, before automatically rejecting agency coverage, ask your insurance company and credit card issuer whether you are fully covered. Consider factors that may exclude coverage such as:

• Renting longer than 30 days.
• Certain models are excluded.
• Travel outside specified service areas.
• Whether or not you carry comprehensive and collision coverage on your own car.
• Violating rental agreement terms (reckless driving, unauthorized drivers, etc.).

Before you take possession, thoroughly inspect the car for any pre-existing damage and note it on your contract; otherwise you could receive a hefty bill for someone else's minor scratches and dents. And, conduct a thorough walkthrough when you return the car.

Bottom line: Don't gamble your precious vacation on simply finding the cheapest deal. Sometimes you get what you pay for.