From what I have experienced, outdoor light is most probably the best, unless you have access to a complete garage studio which allows to get rid off every single shadow possible if you’d like.
As well as offer any kind of tone accentuation depending on what you look forward to as a render.

Early fall, middle spring seasons lights, are the best to my opinion, and it is much better to take pictures in the morning and in late afternoon.
Morning light offers warm tones : as the sun goes up, the light tends to warm tones such as orange, then yellow, and white
Evening (late afternoon) light offers colder colors, which tend to the blue spectrum (channel).

But all these are “personal” choices, depending on the effect you want, other choices may correspond better to what you’re looking for.

Regarding the angle, unless you want to shoot details, parts, I think the best angle possible is “3/4”, like a portrait.
And never forget : you’ll have to kneel, or bend to be at the same height or at least close height as the vehicle is.
Being at the same level as the subject is, gives the most objective image possible.
It is a bit like a pool or snooker game table : the more you bend or lean, the better the ball trajectory will be. thumbsup.gif

Winter season lights and summer season lights are usually very strong, with (too) much contrast, the difference between the shadows and the lights is way too big and usually causes over or under exposure, even with a digital camera which cannot cover all the exposure range.

Concerning the location, outside is preferable, especially grass, for some reason, if a car is in good condition or all “shiny”, this gives a kind of a very classy touch to the picture.
Inside, with artifificial lights, the flash is often “mandatory” unless you have a tripod, and this kills perpectives and increases the contrasts between shadows and lights.
Inside, it is much better to use a digital camera as it chooses the corresponding type of light automatically which cannot be done with a regular SLR with films unless you choose “artificial light dedicated films”.

The 3/4 position means that the picture is neither a full profile (left or right), nor a front picture, but an image in between.
For example, your avatar picture is a 3/4 portrait picture.

The same level as the object means that for example, when you take a picture of a child, if you stand with all your height, you “squeeze” the perpective not being the same size as the child is.
If you kneel, then you face your subject, being in an equal position which is way better to take good images. icon_wink.gif thumbsup.gif

Natural all the way.