Some but not all car rental companies are out to rip you off and pad their pockets with your hard earned cash. Steer clear of the following forms of highway robbery.

The insurance hard-sell.

Anticipate to be pressured to sign a loss damage waiver to limit your liability with some companies. But at $60 to $250 a week, is it necessary? “Consumers may already be covered independently vehicle insurance policy whether it includes collision and/or comprehensive coverage,” notes Consumer Reports. “Some credit cards have protection. Just make sure the individual policy covers rentals and business travel and that it pays the ‘full value’ of any loss, administrative fees, towing and ‘loss of usage.’ ” Also, understand that credit cards are almost always secondary. What this means is that they will pick up the tab after your personal insurance leaves off. Make sure you check with your credit card and get it in writing!

Your defense: Call your insurance and credit card company before hand to find out whether it is possible to avoid a pointless purchase. Only in the case you are not covered already, get the rental add-on policy or scour the Internet for third-party companies that offer coverage.

Also be wary of rental companies requesting huge deposits if you decline the insurance plan, or threatening to not rent to you whatsoever – that’s illegal in most states. When you get these threats, talk with a manager. Do understand of course that if you are not properly covered for the vehicle, rental car companies do have the right to deny you the rental without sufficient coverage and/or a security deposit. Read over the contract thoroughly.

Who made that dent?

After turning in a car and going on your way, you might learn you have been charged for dings and dents you didn’t cause. However, if at pickup you signed a form saying there was no damage whatsoever, you are going to have trouble making an “it wasn’t me” protest.

Your defense: Take photos or video with a digital or camera phone when you initially get the car – and again whenever you return it. Be sure you get close-ups of all existing blemishes, dings and scratches. Pay very close attention to bumpers, windshield and undercarriage.

Most rental car companies are not “out to get you”, but always ensure that you protect yourself. Take shots of the mileage and fuel levels at both check out and return in addition to noting the damage. Pay special attention to the inside of the vehicle as well as their may be pieces missing or damaged.

Fuelish omissions.

Recent surveys said that car rental companies at 13 airports were charging as much as $9.29 per gallon, a lot more than twice the rate at the pump, to fill the tanks of cars whose renters had promised to return them full. Plus some agencies add yet another surcharge for the “service” of filling the tank. Remember, if the fuel pricing is outlined on the rental agreement and you sign accepting it, you are fully responsible for paying that amount if it is not brought back at the same level.

Your defense: Find out where there’s a service station near the rental agency and always, always fill up the tank to the level it was when you rented on the way to return the vehicle.

And think twice about any “fuel option” where the rental company bills you a market-based price for the tank full of gas that is included with the automobile, and then allows you to return the vehicle less than full without any charge.

The catch: The company gets any leftover gas and you get no credit on your bill. To make this system pay, you’ve basically got to be running on fumes when you turn the vehicle in. And who wishes to risk coasting to a stop a mile from the lot?