black cars are tough to learn on. Heck, black cars are tough even when you have some experience.
Just yesterday I had a discussion with a youtube keyboard warrior who claimed that what I was saying was completely incorrect. Here is what i stated:
"you cannot light a black car by throwing light at it, you can only do so by introducing highlights into the paint to bring out the certain details you want to show"
I bring this up because you mentioned getting a reflector to bounce some light back at the car. The answer is this. If you can get your hands on large white reflector that is about 10' or so across (in white) go for it, if not stay away . This goes back to my statement above about not being able to light black cars by throwing ilght at them.
The theory is correct, that i am fairly certain off. Now my explanation might not be as I have been thinking about this long and hard on the way t and from work these last couple of days.... here is an observation i think you might find interesting. Next time you are on the road (preferably morning or evening) take a look at the different color cars. What you will find is that the closer the color is to black, the less reflections you see in it, with black being the closest to mirror-finish and white barely showing any reflections at all. Tell me if I am crazy, but i found this to be true about 95% of the time (obviously depending on angles of incidence, lighting, car dirt, etc etc., we are just talking general trending here)
Now, here is the reason. Black, what is black? More importantly, what does it do? Black absorbs all light. Opposite of white, which reflects all of the visible spectrum (correct....? or am i wrong?) So theoretically, what happens to black if you shine more and more light at it? It absorbs it, correct? here is where the keyboard warrior again told me I am wrong. He sad, "if it absorbs all light, then it would be impossible to have ANY reflections, and anyone knows that any glossy paint shows reflection!"
I said correct, keyword there being Clearcoat (the FINISH) "WRONG!" he says "the clear coat is just that, its CLEAR therefor it has nothing to do with reflections" that is where I stopped my debate with him and let him be.
But lets look at what reflections are. Reflections are the direct result of the surface finish. The smoother the finish the more lightwaves can bounce on the surface and continue on at the same angle back to your eyes, lens, etc (angle of incidence) now when you start having imprefections in your finish (like without a clearcoat which is buffed to perfection) some of these lightwaves dont bounce at the angle of occurance but rather shoot off in many different directions. Well, the more waves that bounce different ways, the less reflection you get.
Now, lets look at a car and how it shows reflections. All modern cars have a nice glossy finish, so you would say, well why is that that i cant see them as well in the white as i do in the black? Here is my reason why. As I mentioned above, white reflects, black absorbs. Ok. So basically, the more light that ou throw at white, the BRIGHTER and more visible it becomes. So what happens? Not only are you seeing the reflections, but you are also seeing more of the color, and the more of the color that is shown the less of the reflections become visible. So with a black car, when light hits it, the "color" (black) does not become any more or less visible, However, as the lighting changes on the background (whether it becomes mroe or less bright) the more, or less, reflections you see.
This is why you can't shoot a black car teh same way you would shoot a white car (especially when using strobes, and anyone that shot strobes and black cars can tell you that you can power your strobe all the way up and blow out the ground, wheels, etc, but the black just stays....well ....black..)
sorry for the long-winded post, but its been on my mind for the last few days and I thought it was appropriate to your situation
here is what I suggest to you, study light, learn light, understand what it does. Further more (as you continue shooting and practicing) look up pictures you like, and try to understand how the light and reflections were used, try to understand what it is abotu the image that appeals to you and how you could go about recreating it. Become more cautious about the surroundings. First learn to shoot with nothing in the background. Shoot just the car and focus on the reflection and the lighting. You can start incorporating backgrounds when you become more understanding of how light works and how you can use it to your advantage.
Its either that, or you shoot in RAW, multiple exposure, and learn to edit like a pro in Photoshop (which is also an option and more and more people are going this route these days )