the one you get once you're infected? Because the preventive one I got was not that much (3 shots, for lifetime I think)

(The shots I got just give you more time to get the life saving shot, it doesn't protect you entirely)

No it isn't. Rabies vaccine is 1ml. The immune globulin that you get with the first vaccine is larger, but still not close to a can of coke. It goes by body weight, most adults will get around 10-15ml.