Have got wrecked playing this far too many times. We call it Beerio Kart fwiw. I like the idea of additional rules, we’ve never been that adventurous.
Definitely got to smash the beer down at the start. Also anything other than bog-standard lager is an error (who bring ans IPA for something like this?!). That Biere D’Or from Tesco is perfect.
Only ever 3 or 4 of us doing it, so we tend to do All-Star Cup on Double Dash in one sitting for maximum effect. Get the Baby Park music stuck in my head for a few days after. MK8 on the Switch is superb though.