These "blemishes" are what truly made the car the Winchesters' home, and ultimately, they were the key to Sam breaking Lucifer's hold during the final confrontation. Key Moments to Remember

Dean attempting to live a "normal" life with Lisa, while a street-light-flickering silhouette of Sam watches from outside. Why It Still Matters

For more deep dives into the lore and episode transcripts, the Supernatural Wiki is an invaluable resource for every fan.