One of the key selling points of the new BMW M5 is its new forged 22-inch Vossen wheels. You can see some photos of the wheels here .
The benefits of material choice in automotive wheels are discussed in this article. Forged magnesium wheels (mags) have a significant weight benefit over aluminum, which can improve performance and safety factors.
Another place where forging shines is in crankshaft production. Read this piece for more information on forged crankshafts.