You will need to reduce the number of trianglers 55771 and vertices 64784.
One examples where you can reduce the numbers:
The wheels are now 4x15 triangles. I would use just 4. More than that is wasted, due to the scale of the game.
That is the first 41 triangles.
You might reduce the numbers of vertices by welding vertices that shared the same coordinate in space as well as on the textures.
Maybe take a look at what I and others have done with quite simple models.
What I would do, was make a low poly model and the render the current model onto the low poly model. (baking/render to textures)
Have a look at that my list of
youtube videos on 3dsmax modeling.
I have use Mike Pickton's: Baking normals, AO and more in 3ds Max (render to texture)
and Clint DiClementi's Baking Ambient Occlusion Maps - 3DS Max.
Also I think Mr Bluesummers has a good one on the subject.
Looking in my thread
VDK Transport around page 43 and on. Here you can see how I used Ambient Occlusion maps to add all the details.