Your new car may very well have an alarm system installed at the factory by the automaker. That alarm is probably pretty decent—but, if you find yourself parking in unsavory areas, you may consider adding an aftermarket alarm. And even if you don't mention this to the dealer, their finance department could offer one at a cut rate price.
As The Truth About Cars pointed out, an entire cottage industry exists that creates alarms that are, at best, simply ineffective. Depending on how they're installed, they could actually be a massive hinderance since dealers may not properly tap into a car's electrical wiring. If you're presented with an "offer" to buy one of these alarms, do your research.
Some unsavory dealers automatically install alarms on every car in their inventory! Run, don't walk, away! Even if you talk your way out of paying for the alarm, you're still saddled with a car that has been questionably modified in a way that very well could violate its factory warranty!!
Car Leasing Concierge will always listen to your needs - there is no pressure for an alarm system, unless it is something that YOU want for your new vehicle!
3. Protecting nothing: Absolutely useless add-ons
A dealer may offer you some genuinely useful accessories—quality rubber winter floor mats and window tint come to mind. But then there's pinstriping, rust-preventing undercoating, paint sealant, door edge guards, etc.. We've even seen fabric protection listed as a dealer-installed item on a car with leather seats!
Almost none of these features serves any purpose whatsoever, and combined they can add hundreds, if not thousands, to the manufacturer's suggested retail price. So while the dealer may knock $800 off of a car's sticker price, they're making that—and more—up by charging you $1,000 for a useless "protection package."
By that same token, some automakers use distributors to service certain regions. To bolster their bottom line, those distributors also add options. While this practice isn't as egregious as it used to be, you should still be very, very wary of anything not installed at the factory.
4. Read the paperwork