what you need is more contrast in your renderings.
GI is good for a even or natural base illumination
but you need accent lights to create highlights and
shadows and thus creating contrast and through this
emphasizing parts of your car.
Besides the typical light stuff recently more and more
artistic representations of car paints became quite
The highlights look like long anisoropic reflections.
I collected a lot of images for my students to look at
and learn from those by observing and analyzing what
makes those images good or bad.
those might be a nice source of inspiration.
Google is a great tool to research visual material today.
This is to even - no contrast, no focus, no drama
This makes good use of negative space but mainly focuses on the side outline of the car
Same use of negative space but the highlights add nice value to the image and you can read the dimension of the
car much better
with a slightly brighter background in side view you start seeing more of the car itself and focus less on the outline
but dont make the background too bright when you want to have some punch too it.
the colors are also important. seeing less of a car but having good focus on some parts makes it look sharp, and attractive to dynamic people.
the lexus color mood is more talking to older classical people - thus think about who you want to address.
here for example the car is too dark for the bright background and hard to read - thus watch contrast.
this one looks eye candy but not dramatic, the highlight reflection is not enough to make the object look more dimensional
natural colors are important to make it look less sterile and indoor/studio shot
reflective bottom and fill lights as well as a designed background will make the car read nice and the background more interesting
Here are images going that direction of anisotropic - stretched highlights. the images are not good. I do not find those once I saw some time ago
feel free to check my picasa albums for more images.http://picasaweb.google.com/www.ckbrd.de