If you want to practice with a specific make/model then poor-man's photogrammetry will be fine, otherwise there are lots of free models out there for you to use instead (if you wish). For quick & dirty previs, I'll often dig up a Sketchup model, export it as OBJs (in pieces) and suck it into Maya.
Are you compositing the car into a photographic image? If so, you'll be match moving all night. If not, then you don't need to bother with photographic textures. Just add some simple colors, and you are golden. Have a look at Hollywood Camera Works (Hot Moves) for examples of shots achieved with very simple models. It looks great, and you'll be working out shots instead of texturing & lighting.
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But, if photos are what you need:
The photos will have lighting baked into the original image. I'd suggest a couple of things to help it look a bit better:
- Take the photos with a long lens.
- Get an existing car model and adjust it to your images.
- Instead of walking around the car & taking photos, leave the camera in one spot & turn the car 90 degrees at a time. This will give you texture maps that look similarly exposed / lit.
- Shoot the photos on an overcast day to flatten out the lighting a bit. You can easily add highlights later, if you wish.
- You may consider shooting the car textures with a polarizer and then slap on a reflection map on the car model afterward. Nothing extravagant, but it'll give you something that looks a bit better, especially when it's animated.
It's not going to look 'real', but it may suit your needs.
ROK