Hi There
Mr. Rob, remember to save as many polies as you can. Sometimes, it´s necessary to judge fairly which objects should be more or less detailed. Just my opinion: I don´t think a fuel rig should have that sum of polies.
In my track´s I´d rather have flat objects with good textures (it works visually, so why not?) instead of a complex 3d mesh.
But keep up your very good job, it looks great.