From my product specialist:
Performance Plus takes one of the world's best sedans into supercar handling territory, while also improving ride quality and range. After hundreds of iterations affecting every detail of the suspension, our vehicle dynamics team was able to achieve the rare outcome of simultaneously improving performance, comfort and efficiency. In addition to upgraded dampers, bushings, stabilizer bars and tires (Michelin Pilot Sport) , the rear wheels are 1/2" wider and staggered for improved acceleration on low grip surfaces. Range improvement is 8 to 12 miles. Requires 21" Wheels, available in Grey or Silver.
Rear wheels are 1/2" wider.