ah you understud what i mean.
i try to explaning you the detail of correction.
its a short session for your model, you just need the split polygon tool.
on the picture i tryed to mark...
on the yellow original is this split line from wheel to nose ending on bottom of carosserie.
but on your modell the horizontal line who crosses trough the wheel area.
there you first delete the edge and remove the lonely vertex #2
this line we wanna ad (edge) is not starting on the end o edges that doesn t matter you can cut with split polygon tool to lines down to the bottom starting (as result of cut) as a triangle (the small black circle) and goes down to bottom.
i hope you will catch it.
you seems not to be a noob, i think yo are already skillful!
if not i will cut for you the model and view public all steps...
: daijobe desu :