Thanks. Looking through everything I took that day I'd say I was generally too close.
A couple of comments.
1) It looks like almost all of your shots were from eye-level. Seriously, cars are 4 feet tall. Many shots are taken from eye-level are a result of a lack of thought about composition (or a photographer with a bad back). Just standing upright and holding the camera on your face, especially with a fisheye, is selling yourself short on composition and creativity. Bend over, look at things square on. Or, try to get up high and shoot downwards. It doesn't really matter as long as it has a purpose. Sure, some shots are best from eye-level, but only a small fraction. Fisheyes are exceptionally sensitive to this problem because of their distortion. It may be a good thing learning to shoot with it because it's much easier to miss this compositional issue when using standard lenses (they don't exaggerate it as much).
2) Don't fixate on getting the whole object in a shot. The only photo of this set I really thought was reasonably well composed was the BMW steering wheel shot. The BMW logo shot wasn't bad, but the angle made it hard to see clearly (though good job of getting down low for that one). It happens that those were the two where you didn't try to get too much into one photo. Just pick a subject and find the best way to highlight it.
3) Look at the edges of the frame. Make sure your subject is actually entirely in the frame. Chopping off 10% of a bumper (for example) looks bad, especially when there is a ton of dead space on the opposite side of the frame. Fisheyes are tricky. If you can't fit those square lines into a frame, try changing your viewing angle (squat down, move to the side, etc).
4) If you have the wrong gear (for example, your lens is feeling too narrow), change your expectations. Pick smaller features, try to shoot down the side lines of the car, shoot the shifter knob. Shoot the hood ornament, shoot the steering wheel, shoot the tires, shoot the leather, shoot someone's hand on a pin stripe.. Shoot someone's face in the side-mirror, even.
Also, don't abuse the fisheye. They are usually annoying if not used with a clear purpose. The one real power of a fisheye is that it allows you to grossly exaggerate whatever is in the immediate foreground, so you have to pick what that is. I've seen some killer fisheye shots of that were accentuating a specific feature, say an exhaust, or a hood ornament, but you have to bend over and put those in the foreground and the rest of the shot is just background. Don't shoot anything with lines that you expect. Try to make them unexpected. It's NOT a wide-angle lens, it's a fisheye. Don't try to use a fisheye as a substitute for a wide angle. In most of these shots, there is nothing in the foreground but the car's roof. If you are trying to draw attention to the roof for some reason, that's great, but I don't think that's the plan here.
By all means, bring your zoom next time, but DONT use it to substitute for bending over or squatting to get a better angle. Try shooting cars from bumper-level and the photo is ENTIRELY different than from eye level. Try to get both wide angle and zoom shots. Details and lines (especially in a crowded place) are often nicer than the whole-car shot.