Just in its first week on sale, Mario Kart 8 managed to sell over 1.2 million copies worldwide.
Mario Kart 8 achieved the feat in just four days spanning May 29th to June 1st. The regions accounted for were the Americas, Europe, and Japan. It was already revealed that Wii U console sales were up because of the game.
Mario Kart 8 might be the killer game the Wii U needs to more sales. The Mario Kart series as a whole has amassed sales of over 100 million copies.