Just purchased a non CPO 2015 750i with 16K mileage and looking for an extended warranty. BMW dealership offering Platinum BMW warranty for $6,700 3 additional years over factory to 100K. Same policy though GWC $3,912 with all bells and whistles (Twin Turbo, luxury package). Concerned over the big difference in price. Thoughts? Any success with other companies? Any to stay away from? I appreciate all ideas suggestions.