Best Sugar-Free Energy Drink? Is there one?!

So, I don't drink them often, but when I am driving and need a boost, they do the trick. I am looking for advice in case any of you gamefuel, errr, energy-drink fans have some advice for me. I tried some Rock Star "JUICED" one which actually tasted ok when it first goes in, but then you get a serious aftertaste of what I can only describe as liquid body odor. What's worse is I picked one up and snuck it into the movie theatre and one sip later I realized what a dumb mistake that was without knowing anything about it.

So, anyone actually ever have a sugar free one that tastes good? I like full throttle fury, and I heard there was a sugar free version but I have never seen it. Thanks!!!