I'm brand new to this game-- as in, I probably just started playing it 10 minutes ago-- I just jumped right into Time Trial and drove a 1'47"540 on MKS. (At least it's not last place!) Donkey Kong, Mach 8, Standard tires, Super Glider. Couldn't figure out how to make the bikes wheelie. Still trying to figure out the fastest combos in this game (which I probably need to unlock) as well as the best startboost timing (I believe it's immediately after the "2"?)
I don't expect to do very well in this game, since a lot of the MK7 mechanics seem to be back.
I also need to go back and finish Super Mario 3D World-- I was just dying to give this one track a quick try. I'll probably do better if I could play it on a Game Cube controller, but there are no ports for it on the Wii U-- guess it needs a separately-sold adaptor.
EDIT: Okay, just got a 1'55"021 on WP. Wood tires here, but same Kart parts otherwise. Hey, I beat Flo

Pretty sloppy run as well. I'm still familiarizing myself with the Wii U pad.