MSNBC travel columnist, Christopher Elliott has some advice for those of you renting a car anytime soon. It seems rental companies "unable to raise their rates or impose significant cancellation penalties on their customers" are relying on fees and surcharges to increase their profit margins. And "they are doing so now with more creativity and zeal, leaving frustrated customers... swearing they’ll never rent again."

Although technically not "scams", these four "profit methods" by rental companies fall in the "somewhat legal" or "gray area" of the law, but in terms of ethical? You'll have to judge for yourself.

First is the biggest: the enforcement of rules to the letter. Picking up your car later than your reservation? You might be charged more because rental companies have different rates for different rental lengths. And where they would have overlooked that in the past, not so much anymore. I had this happen to me on a trip to Atlantic City earlier this year. I returned the car a half-hour past the time due and was charged full rate for an extra day. I called the customer service number, spent an hour arguing that 30 minutes is not a day, and they refunded my money. But how many people spend the time to do that? The rental companies are betting not that many.

Second, Elliott advises you make sure the gas gauge is fully on F. Rental companies have gotten anal about exactly what constitutes "full" and how far you drove from the gas station to the rental return. A hair below will get you a gas charge now, he says. Bring your gas receipt to prove you filled the tank.

Third on Elliott's list is the "damaged car" scam. If you're not diligent about checking for damage to the car when you pick it up, you may get charged for damage someone else caused when you drop it off. Elliott advises going so far as to photograph the car both at pick-up and drop-off to cover your ass.

And finally, check your rental agreement for any "hidden" fees - especially if you're a frequent renter - like drop-off fees that they waived for you in the past.

You can read the whole article here.