[UPDATE] NewEgg's product description for Mario Kart 8 matches the game's Fantendo Wikia description, which calls into question is validity. We're still waiting to hear back from Nintendo for the official word.
The original story is below.
The NewEgg product description for Wii U game Mario Kart 8 suggests the upcoming racing game will feature a series-first track editor. New elements in Mario Kart 8, according to the product page, include "designing your own tracks," though no other details are available.
Nintendo has not announced track-editing functionality for Mario Kart 8 and product pages on third-party retailer websites are not necessarily always accurate. The product pages for Mario Kart 8 on GameStop, Amazon, Target, and Best Buy do not mention this functionality.
So for now, definitely take this news with a grain of salt. We've reached out to a Nintendo representative for comment.
Nintendo previously confirmed that karts in Mario Kart 8 will be customizable, just like they were in Mario Kart 7 for 3DS. Other new features for Mario Kart 8 include Mario Kart TV, which allows you to share videos on Miiverse--and anti-gravity tracks that let you race upside down.
It was also recently confirmed that all seven of Bowser's minions--the Koopalings--will be playable in Mario Kart 8. The game launches for Wii U on May 30.
Would you like to see a track editor in Mario Kart 8? Conceivably you'd be able to use the Wii U GamePad to build your courses, which seems like it would work quite well.