Renting a car sometimes feels as high-pressure as buying a car. The agent urges you to upgrade the car, add GPS and buy rental car insurance — and it's not for your benefit. Car rental companies make 10 percent of their revenue from add-ons, according to the Consumer Federation of America: "stuff we opt for at the counter because of convenience, or a hard-sell."¹

Have you encountered these five common rental car upsells? We take a closer look and tell you how to avoid them.

1. "You're Going to Want to Upgrade Your Rental Car to the Full-Size."

Ed Hewitt recounts the case of the phantom Beetle car rental scam on Independent Traveler. Having arranged to rent a standard-sized car, Hewitt's wife was told by the counter agent that her bags probably wouldn't fit in the Volkswagen Beetle that had been reserved. The agent recommended upgrading to a full-sized car for $160 more — and also mentioned the Beetle didn't have air conditioning or power windows.

Irritated by the company's subterfuge, Hewitt and his wife decided they would try the Beetle anyway. When they got to the lot, the attendant handed them the keys to a Kia Optima. There was no Beetle on the lot. "I told them to stop telling people that, but they keep doing it," the attendant said. "We don't even have a Beetle here."

Resist the pressure to upgrade your rental car at the counter, unless the company is offering upgrades for extremely low rates because they're genuinely running short of smaller cars. Check the company's website ahead of time to make sure you know which cars are considered economy, compact and standard. If the counter agent gives you a hard time, do what Hewitt did and call the corporate number. The representative you speak with isn’t operating under the same sales pressure, and so may be willing to help you get the rental car you were expecting.

2. "You Need Rental Car Insurance, Because Your Insurance Won't Cover You."

Rental car insurance is one of the most common upsells you'll encounter when renting a car. It's easy for an agent to convince a customer that their insurance doesn't offer enough protection, or that the insurance requirements are different in another state. In most cases, your regular car insurance will cover you — check with your insurer before renting a car. Here are the four types of rental car insurance the company will try to sell you:

• Supplemental liability insurance typically covers damages to other people's property and medical costs for injuries you're responsible for.² If you're already insured, you're covered.
• Personal accident insurance includes medical, ambulance and death benefits for you (the rental car driver) and your passengers. In most cases, your existing health, life and car insurance policies offer the same benefits.³
• Personal effects coverage covers the theft of possessions from the rental car. Most likely, your renter's or homeowner's insurance policy already covers this situation.
• The collision damage waiver/loss damage waiver lets you off the hook for paying for rental car damage or theft. This is the one type of rental car protection that makes sense to purchase, but don't buy it at the counter. You'll save money with the OneTrip Rental Car Protector from Allianz Global Assistance, which provides collision loss/damage insurance coverage up to $50,000 for just $11 per calendar day.

3. "Don't Worry About Filling Up the Tank. We'll Take Care of It."

The tank fill-up is the simplest rental car upsell. The agent offers to include the cost of a tank of gas in your rental agreement, so you don't have to worry about stopping by a gas station before you drop off the car. The price quoted is almost always more expensive than the cost of simply filling the tank yourself, however. It's not worth it.

4. "The Tolls Will be Included in Your Bill."

If your rental car road trip takes you through a state with all-electronic tolls, you have two options: renting the company's transponder, or agreeing to let the company track unpaid tolls and add them to your bill. Beware: Both ways allow the company to charge you huge fees. Rental car companies charge as much as $20.49 per day to rent an electronic transponder.⁴ If you opt to pay the tolls later, they may charge "administrative fees" every time a toll is paid. One couple sued Dollar Rent A Car in 2014 after they were charged $60 in fees in addition to $4.70 in unpaid tolls.⁵ The good news is that by 2016, states' electronic toll systems will be synced so that travelers can bring their own toll transponders when renting a car.⁶

5. "Just Sign Here."

Even if you've stated clearly that you do not want additional insurance coverage, unscrupulous rental car agencies may trick you into agreeing to it. That's what happened to numerous customers of Dollar Rent A Car/Thrifty Car Rental, a class-action lawsuit alleges.⁷ Customers say that after they declined the extra insurance, they were presented with a small-print contract on an electronic tablet and were told to sign. Only when they returned the car did they find they had been charged hundreds of dollars extra for the unwanted insurance.⁸

What can you do to fight rental car insurance scams like these? Take your time and read the fine print before signing, even if the agent tries to rush you. Ask what the total charges will be, so you're not surprised by extra fees.