Think a silky engine and uber-glitzy exterior shell are all it takes to sell a new car? Oftentimes, you'd be wrong. The real key to selling a car is its interior. With data increasingly showing that car interiors are one of biggest selling points, carmakers have turned their focus to interiors in a bid to attract new buyers. Here are nine of the most dynamic rehabs undertaken on new-model cars. We were not surprised to find that GM has four models listed.