Coke Vault 'Energy' Soda

Looking for something to drink in the soda machine at work today, I noticed what I thought was Mellow Yellow (I could only see the back of the bottle) in the Coke machine (we have one of those fancy glass-front machines with the traveling belt that retrieves your soda). It turned out to be Coke's Vault soda.

It seems to be somewhere between Mellow Yellow and Mountain Dew in taste; not as strong as Mountain Dew's syrupy flavor, but not as mellow as Mellow Yellow. It also has a bitter bite to it, no doubt from the high caffeine concentration in this stuff.

Not terrible, but I don't think I will select it by choice if the other two are available.