Test track puts you in a "test" car and drives you through the tests that cars go through for safety and such. It is similar to Dinosaur, but at the end you go about 60 MPH around the outside of the building. Can be scary for some young ones, but I find it fairly tame, It's like going 60 in a convertable.
Mission Space is only similar to Body Wars in the sense it is a simulator. You are put in a smallish cabin with 3 other people and the screen / controls move tword you. Each indiviual has thier own screen to watch (remember to always look forward) and you go through the felling of lift off with the appropriate G-Forces as well as a little feeling of weightlessness. This is accomplished with a centerfuge, think of the other rides that stick to you a wall and drop the floor out from under you, however, this is setup so you do not know you are spinning, unless you turn your head to the sides. Some people love it, some hate it, I myself love it since I have always wanted to go into space and it will be the closest I will come to weightlessness.
I hope this helps. Feel free to ask any other questions.