I think I've made a bit of a discovery yesterday:
I initially started my ride with water mixed with Hammer HEED. It tasted REALLY bad (I don't think I mixed it up correctly), but I noticed that every time I drank it (which wasn't often, obviously), my performance was sustained and the effects were immediate! It really did make an impact on feeling comfortable during my ride.
I eventually had to ditch the stuff and switched it out with pure water. I drank a LOT more, but it wasn't really helping with my performance. I was still doing fine, but it didn't feel the same.
When I ran out of water, I loaded it with Gatorade. REALLY bad stuff. Tasted good, but that was mostly because of the sugar. Sugar is quite addictive, and it didn't help much with my performance either. Just made me drink a lot more.
I then switched it with Gu2O, which was okay.