I'll take any criticism on how to improve as well.
I love the parking garages, they're fun for photography and to be noisy in.
As for critiques.
Lighting. Your car is parked with the shadows facing the camera.
Contrast. Due to the lighting and shadows the car appears very black and details are hard to make out.
Framing. Your car is positioned in the shot in such a way that other elements drew my focus away from the car. The first picture it is the light and the arrow, second picture its the long stretch of open area next to the car.
Those are the things that stood out to me right away.
Here are two posts I suggest reading.
First is a basic overview.
Then
this second link is a fantastic reference in automotive photography. It covers the basics and makes them relevant to cars, along with giving you picture examples.
After reading the second link, you can hop on flickr and look through the different car groups and car pictures. See what other people did, in the context of what you read earlier. Look at your pictures and see what you don't like about them, where you can improve.
If you liked the reads I linked, Google around for more guides and information, there is no right or wrong answer and the more perspectives you can get the better. I'm a big fan of reading.
You're off to a good start and picked a sweet location.
Hope the constructive criticism helps!