The first photo is quite busy. The dynamic range in that scene is high. => blown sky with very dark front bumper.
The second one is better as far as the exposure goes. Shoot it in portrait mode without tilt maybe better. The super bright yellow area is not helping either because it draw attention away from the subject.
The strong yellow, blues, and reds are very contrasty and resonate... at the expense of losing interest in your subject which isn't a good trade-off. With portraits, what the person is wearing and the background you put them against is critical. You want outfits and backgrounds that don't contrast and don't draw attention.
In the car pic, look at alllllllll that stuff in the background. None if it has anything to do with your subject. Leave it out. Also, the front of the car has lost most detail because it is underexposed (you exposed for the background). You generally want your subject to have detail.
These are two very important concepts to harness so you did well choosing these two photographs to post for feedback.
I am bored today... so played around with your images. Just to give you a better idea, on the cropping and exposures. I am lousy at photoshop.. and I did these quickly, so don't judge the quality.. just look at them as guides! (and yes.. fellow TPF'ers.. you are allowed to laugh at them!)
changed canvas size, did some quick cloning... and cropped. Need to learn to use Content Aware Fill! lol!
Fake HDR.. 7 different exposure values.... and a little blue in the sky...