I’m using blender 2.49b on windows 7 and I can’t enter game mode with the scene in the attached blender file, The cmd window says the engine has started and ends when I hit esc, only, the game window never switches to show the game. I’ve even tried appending the scene into a fresh blender window. Still doesn’t work. Fresh blender windows go into game engine, just not this scene.
car testi with empties.blend (278 KB)
You World is damaged. I do not know what it is but at least fps:1 makes no sense at all
I did not know worlds could be damaged. Probably because I started modeling in 2.53 but gave up and returned to 2.49, something I forgot to mention. It enters game mode now, but 1 fps?!? I also have no idea why the car is rotating and when I put a plane under it, the colored wheel rises! 
If you want to build a car have look at the VehicleWrapper for Non Programmers. This schould makes it a bit easier for you to assemble a car.
By the way: there is no real need to use armatures for a car. The most parts do not change shape.
How did you know I tried using armatures? I thought I had deleted those after I read they won’t do what I thought they could. Car wrapper looks neat, though the point was to learn how to use the game engine, but if I can understand the wrapper, it’ll help.
You still have some armature modifiers :). They are not set up properly (no armature name) and they will not work in BGE (in BGE the skin mesh object must be parented to the armature).
The wrapper is a helper to apply the car physics. This is because it is really difficult to set up the car physics with rigid body constraints etc…
The VehicleWrapper is an Python interface (API) allowing to set up a car body and attaching wheels. You can configure some properties such as suspension, damping etc.
To make it drive you can add forces for brake, drive and steer.
All this things are available by Python function calls only. There is atutorialaround describing how to set up the scripts to use the VehicleWrapper API. You can check that if you want. Then you learn how to set up the parameters in python.
If you want to concentrate on modelling cars, you can use the template in the above thread, without worrying the Python code. This template uses the same API as the tutorial.