Each "flavor" corresponds to nutrition you would receive from the soft drink. The liquid color in the bottles was meant to resemble oil and go with the theme. I researched some 50s slang to make the packaging have an even more vintage feel. On each bottle they read:

 

Elbow Grease helps with those mornings where you can't just get up and go. It revitalises you and helps give you that extra kick you need to get on the stick! Elbow Grease will land you in fat city!

 

Parts has extra potassium to help prevent muscle cramps. It's on the level, especially for those work-outs you do to impress that special someone in your life.

 

Know How is a special blend of ginkgo leaf and a minty additive to get your mind going when YOU need it to. Perfect for that job you have been after.

 

Paint Job is enriched with vitamins a, b, c, d and e for healthy skin. People will complement your classy chassis in no time! You'll be in orbit with the hipsters faster than you can blink.