Smart, Intuitive, and Functional Superpowers

Nine hours in a car driving up the eastern seaboard gives you plenty of time to think, and if you have nothing to think about, you have to come up with something. That said, here are a couple superpowers I'd like to have and the realistic connotations behind them:

1) The ability to store potential energy. Basically imagine having a giant rubber band holding back whatever part of your body you wanted to stash a bunch of energy in.

So you rear back to throw a punch, have that energy build up for a second or two, and then as if the rubber band snaps, you launch forward with a thunder punch that could smash a concrete wall. The same energy would protect you from shattering all the bones in your body when you do make contact, so kicking through a sedan wouldn't snap your leg in two.

You could also use it to leap farther or higher.

2) The ability to move as fast OR as slow you want. Slow is important too, so in case you fall off a building, you can slow yourself in the final 2 seconds and come to a gentle landing. Or if you wanted to be dramatic, you could spend 45 seconds jumping through the air.

Moving fast would put a spin on your relativity, so the faster you go the slower everything else looks. It might not be so useful for things such as traveling across the country in under a minute, because despite moving so fast, the whole trip would still feel like its taking forever for you. Also the effects of aging would be an issue, so the more you used your super-speed power, it would compound on your aging and youd age faster than your normal-people compadres.

The whole power would be less about your ability to move at a custom speed and more about your ability to control your own personal time. You'd just wind up destroying yourself if you were able to move your body at sonic speed anyway; your muscles arent supposed to function like that.