According to Miyamoto, the GameCube Mario Kart title has already undergone localisation for North America, which has been completed. The title should be shown at E3, and will have several new innovations.

Update: Clarification on the report, apparently the game hasn't been localised for North America yet, it isn't even finished. It was a bit of misunderstanding from Miyamoto saying that some North American voice recording had been completed.

On the note of online possibilities, Miyamoto said this, "We've been conducting online experiments with Mario Kart for quite some time. This time around, we've looked at it and I still feel that [the kind of experience Mario Kart delivers] would be very difficult to pull off online."