Negotiating a car price can be exhausting. And just when you think you’re all done, you may discover — thanks to add-on costs — the price you’ve agreed on isn’t the one you’ll actually pay. In fact, you may even be told you can’t get out of it, because the add-on has already been added to all the cars on the lot.

It can be tempting to throw in the towel and just agree, rather than face the prospect of doing this all over again at another dealership.

But what if some of the things they suggest sound tempting? Are they ever worth it? Some may be, if it’s something really important to you (say, pinstripes). Others (rustproofing, anybody?) may not be. If you’re buying a new car, it has already been treated; a supplemental treatment is likely not necessary. Here are some others you should consider carefully.

If you’re buying a new car, it has already been treated; a supplemental treatment is likely not necessary. Here are some others you should consider carefully.

Fabric Protection

Your car should already have upholstery that wipes up fairly easily. Car manufacturers know we spill things, and they design cars accordingly. If you want additional protection, you can buy a spray-on fabric protectant and apply it yourself.

Mike Quincy, auto content specialist at the Consumer Reports Auto Test Center in East Haddam, Conn., told Bankrate that new cars don’t need it, and that humans could actually do without the chemical exposure.

VIN Etching

VIN etching can be a good thing — and police and car insurance agencies recommend it. It may even save you money on car insurance. However, having the dealer do it can add more than $100 to your cost, according to the Consumer Law Group.

You can buy a kit and do it yourself for $20 to $30. Also, some police departments will do this for a small fee.

Extended Warranty

Particularly if you are buying a new car, you probably don’t need an extended warranty, and the money would be better spent getting all the regular maintenance done.

After all, problems caused by failure to do routine maintenance are not typically covered by a warranty, anyway. An exception may be if you are buying a car that is extremely expensive to repair.

In general, new cars tend to be reliable and Autotrader recommends against them, as veteran auto writer Doug DeMuro wrote recently.

Credit Insurance

What would happen if you became disabled, couldn’t work and couldn’t pay? Credit insurance might make sure that payments are made for a certain period of time or even that the vehicle is paid off. There are different kinds of insurance, with different conditions. All will increase your car payment. The Consumer Financial Protection Bureau suggests giving it some thought and checking to see if there are less expensive options available. You do not have to sign up the same day you purchase your vehicle.

The Consumer Financial Protection Bureau suggests giving it some thought and checking to see if there are less expensive options available. You do not have to sign up the same day you purchase your vehicle.

Also, beware of “menu-selling” at the finance office, where you are asked something like, “Which of these warranty options do you prefer?” and opting out is not among the choices. In many cases, you can opt out; it just isn’t in the document.

Ask.

Even if you do decide you want one of the options offered, you don’t have to buy it that day.

According to AutoTrader, you can buy an extended warranty for your car after you buy, and “any time before the car’s manufacturer warranty expires.” You may prefer to decide at your kitchen table, rather than at the dealership.

How to Get (Only) What You Want

It is important to go over every item listed on the invoice — and the “supplemental invoice,” which may contain dealer-added options, like paint protection or nitrogen-filled tires (neither of which is essential). Make sure you understand and agree with the charges.

It can be hard to walk away once you’ve invested so much time and energy. You may need new wheels, and have spent much of the afternoon test-driving, then negotiating… and be willing to fork over more than you planned just to have this whole ordeal be over, and who could blame you? You’re tired, and you just want to go home.

A possible alternative is to go in only to decide which models and which options most appeal to you — and then check with your insurance agent to see what they would cost to insure, particularly if a difference in cost would influence your decision about which to buy.

At that point, you can call or email dealerships and ask them for their “drive-out price,” including tax, title, delivery and any other charges, of the make and model you want with the options you want. Many dealers actually have an Internet department accustomed to working this way. That way, you know exactly what you’ll pay before you walk in.

You take a test drive, and if it’s as expected, go sign the paperwork. If you enjoy the “sport” of the haggle, this may not be for you. But if you like comparing prices without having to sit in multiple managers’ offices, this could save you time, and possibly money.

You could go a step further and get financing approved from your bank or credit union before you go to the dealership.

Getting your credit in top shape before you begin shopping is smart anyway; a good credit score will help you qualify for the best interest rates. If you’re not sure where you stand, there are many ways to get your credit scores for free, including through Credit.com.

And if you want add-ons, you can add them on later — and know exactly what they cost.

This article originally appeared on Credit.com.

This article by Gerri Detweiler was distributed by the Personal Finance Syndication Network.