1.Make sure you switch world coordinated axis in Maya or MayaLT to Z up. (This can be done in the preferences window. Realign vehicle or build new facing X forward)
2.Make sure your pivot transformations for all meshes are reset (example: transform, rotation, scale = 1,1,1. use the freeze transformations option)
3.Make sure your Wheel pivots are centered to your wheel mesh. (use the center pivot option, then bake pivot)
It is important to bake pivot! Your wheel pivots make be positioned in the center of the wheels on screen, but they are still calculated at zero offset after freezing transforms and exported at center of world (x 0, y0, z0)
I come from a max background, and this was new to me, and caused a big headache. Hope this helps anyone. Thanks