I am from Newcastle in the North East of England and there is a story about the renound "Newcastle Brown Ale" In the past it was very heavily carbonated and there was a special ward in the city hospital for those who became addicted to it!
It's 4.7% ABV, AND so not rediculess in strength however it was said to get you drunk very quickly and this was due to the co2.
Aparantly co2 speeds up your body's absorption rate of alcohol! I wonder if you can Tanzan would have the same effect if mixed with a spirit!