Notice, if you will, the part "and some automakers will void the factory
corrosion perforation warranty if the car is undercoated by a third
party"......



Rust-proofing

Although new cars no longer need it and some automakers will void the
factory corrosion-perforation warranty if the car is undercoated by a
third-party, this hasn't stopped some dealerships from promoting
undercoating as a dealer option, says Mike Quincy, auto content
specialist at the Consumer Reports Auto Test Center in East Haddam,
Conn.

"Cars leaving the factories today all have excellent rust-proofing,"
Quincy says.

"(Dealers) have an incentive to do it because there's a fair amount of
markup they can get on these services," he says.

Dealer-applied undercoating can range from $200 to $1,200, depending on
the car, the type of treatment package (basic or premium), and whether
it includes an extra option, such as sound-deadening. Moreover, rust-
proofing can be sold to the new car buyer as a separate dealer option or
be included in a pricey bundle called an "environmental protection
package" that also can include paint sealant and fabric protection


Read mo 5 Dealer Options To Skip When Buying A Car | Bankrate.com
http://www.bankrate.com/finance/auto...-to-skip-when-
buying-a-car-1.aspx#ixzz23uNIhNCT