Well, look at the beige Lumina. The top of the headlights / front of the hood lines up with the top of the wheel well. The hood slopes up to meet the windshield. It doesn't need to be a box to not be very sleek. And since it's at least one part Thunderbird, it needs some sleekness, and I want to keep the headlights fairly short and long.
Look at that. I'm not following the guideline I just mentioned.
It's no wonder it keeps feeling a bit too tall when I try putting it in game. The wheel wells are a bit too shallow. It's amazing how much a small height difference can affect a car's feel.
I think I can do a few things here:
Acknowledge that the Lumina is not an especially small car
Acknowledge that the Hero is supposed to be a small truck
Make the Capital longer in its hood/trunk regions and possibly a touch wider
Revise the exaggeration of the height difference between the hood, trunk, and bottom of the windows