OK,

I called my local Hyundai dealership and they said if I was to put Bosch Platinum +4 spark plugs in my Santa Fe that would void my vehicles warranty!

I called Hyundai Motor America and they basically said that if you use any other type (manufacturer) spark plug other then Champion or NGK and if those spark plugs cause a mechanical problem then your warranty is void.

Of course it would be Hyundai's burden to prove that indeed the mechanical problem was caused by the spark plugs.

My local dealership did say that the spark plugs on the v6 Santa Fe has to be installed by them because of the need to remove the intake manifold stuff. They said it cost $129 for a spark plug change....I hope that includes the price of the spark plugs too!