Besides, if they use salt on the roads where you live during snow or ice events you will be mighty happy you bought the rust proofing 10 years from now. I've seen the undersides of a few cars from out east and up north (areas that use salt on the roads) and the under carriage rust is terrible bad.
Yes, in this day and age the steels that go into making these cars is worlds better than what they had in the '50's, '60's, and '70's but it is not going to stop the corrosive properties of all that salt. Most people don't run to the car wash and manage to get all that salt sprayed off the underside of their car after every snow storm, so it just sits there on the metal corroding the steel and under carriage components.
If you happen to be lucky enough to live in an area that uses the road spray solution instead of salt, then you may have paid for nothing in terms of rust protection. The spray solution they use does not contain anything that is anywhere near as corrosive as salt. I remember last winter when the temps dropped, the spray trucks would run and lay down some of that spray, characterized by the 4-8 lines it made on the road surface. The spray lasts for about 4 days until it washed away and needs to be reapplied.
Current love affair: 2004 SVTF #953 (Josephina - pronounced hoe-se-fin-a)
RIP: 2002 SVTF #2358, Sent to graveyard on June 11, 2013. I will always remember the good times we had!!
This car made my hair go gray, and did not care.