I'm a pretty avid photographer myself

If you don't mind me asking, what are you doing the HDR for? I honestly don't find them that cool for car photos unless you have a city / night scene background. They also are good for LED lighting schemes.
I would get closer to the car and bring your FSTOP down to where the car is in focus, but the background is blurred. Maybe put it on a tripod around the height of the headleights at an angle off the side of one of the headlights, like maybe 15 ft off? I like your angle. I always use geometry when doing my shots. It's like you were drawing a triangle, and one line goes from the camera to the far headlight, while the other line goes from the camera to the rear of your car. The middle line (where you are shooting), goes to the closer headight, and that would be your straight shot. The farther back you go, the wider the angle. It looks sweet! Also, if you switch sides or reposition the car, you may be able to get the guard rail out of the photo.
Check out this shot. Notice how the bridge is blurred a little in the background. I wanted to try some more shots, but it started raining! I wanted to blur the bridge even more.