Is undercoating worth the extra money? Does it reduce noise?
It may reduce noise, but it has the potential to INCREASE the possibility of rust on the chassis of your car. Today’s cars are given such good rust-prevention at the factory that after-market rust treatments are unnecessary and are frequently counter-productive. Of course, that doesn’t stop car dealers from trying to make extra profit from this now unnecessary procedure.
Save your money, and skip this stuff. Instead, during the winter months, just make sure that the underside of your car is sprayed frequently in order to rid it of road salt. Most commercial car washes have this as an optional procedure for a dollar or two extra cost. For the many hundreds of $$ that you would spend on undercoating the car, you can have your car thoroughly washed each week during the winter for several years!
It it’s done properly, it can reduce noise and not increase the chanceof rust. When the coating is applied, it could plug the body drains. The coating can also create spots for water to pool if it is not sprayed on right. If you can make sure the job is done correctly, it might help with noise. This is only for a new car. I don’t think you can properly prepare a used car at a reasonable price for a good undercoating.
In my opinion, it’s not worth the money. As said above, modern vehicles are no longer likely to rust. It might slightly reduce noise, but not much. Save your money.
No and no. Modern cars are well protected against rust. Anything added afterward isn’t going to help and may make things worse. Save your money.