Hi Niklas - vehicle modeling tends to be one of the most difficult categories to model.

You might try lofting most of the body with the Loft style = "Loose" option, see these previous threads for some examples:

http://moi3d.com/forum/index.php?webtag=MOI&msg=7366.1

http://moi3d.com/forum/index.php?webtag=MOI&msg=6058.1

- Michael