Tool assisted speedrun for the new SC done on PAL with the Bizhawk emulator. Would be a 41.83 on NTSC. There seemed to be some potential to use your mushroom 1 frame earlier on laps 2 and 3 and still get the jump but I wasn't able to get it. Could be possible though. Not unreasonable to assume this time will be matched by humans on console.
New Rainbow Road Shortcut FAQ: https://pastebin.com/MfmjALHB
Mario Kart 64 Players' Page: http://www.mariokart64.com/