I think the brightness near the center is fooling the camera's exposure calculation. #1 is very very dark in the grill of the car, no detail at all, yet the windshield, hood (or bonnet) and roof are white-out. #4 and #5 don't have that extreme highlight at the center and are much better exposed.
There's still the problem of tilting. Serge, you gotta find some way to check that the camera is level.
Everyone's telling you your ISO settings are off, but I disagree. You have bright highlights in the center of some images, which fools the camera into darkening the picture. Your camera's lattitude (the range of exposures it can present on a frame, dark to bright) is apparently quite low. In the film world using a slower film (lower ISO) would help, but I'm not sure that applies to digital. Try it, though. If your camera is set at ISO 400 or 800, drop it to 200, or even 100 if it will go that far. Explore the menus, it's probably in there somewhere. Regardless, avoid extremes of exposure near the center of your frame.
There may also be an exposure compression in whatever image software you are using for your pictures. We don't know what that is.
I'm thinking #1 is a crop of #2, not a different shot at a different zoom, because there's absolutely no change in perspective. Your lens tends to push the corners away at wide angles, meaning that what should be a straight line curves out or up at the corners. Nothing you can do about it except avoid extreme wide angle zoom. Try zooming in and stepping back to eliminate that. It'll be hard to pick up on the LCD screen or viewfinder, but if you look at the pictures carefully you'll see what I'm talking about. For example, the white wall with the flowers in the windows that I "levelled" you can see that although the walkway is level and the door it leads to is vertical, the window at the right of the frame leans out. In your original shot that window is only slightly left of vertical while the corner past the walkway is very far left of vertical. That's the distortion of your lens, and like I said, you have to live with it, or avoid it by not zooming out all the way if you can help it.