"bouncing IS the order of the day" but, maybe a bit of direct light on just the tires to bring the tread up to the overall level of light. Hint: don't clean the tread - the dust helps here. Other than that, we almost never used direct light on the car.
We used huge 15X30' frames (on casters) covered with cloth to reflect into the car. Some were hung as overhead flats. These were lit with 20K lights. Smaller, highlighting reflections were lit with 750's. Check out the studio here: Stage3
The shot below was done using a 4X8' piece of plywood painted white at the camera. (This was my 1st real "Car shot", as in paid for by a manufacturer) 
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Try a few shots with the cars lights on for part of the exposure.
If you're doing interiors, start with some light bounced off the headliner. We would put a 30X40 white card up there & hold it in place with those "S" hooks they use for hanging curtains.
An alternative/addition to studio would be to shoot outside if it's overcast & the sky becomes an overhead flat. Just after sunset is great! You'll need a BIG, uncluttered area like a BIG parking lot
behind you to minimize crap reflecting into the car.
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If you don't have an assistant, get one for this shoot or you'll go nuts trying to move lighting & running back to see what it looks like. (If you already have one, then get TWO!) You might want to practice beforehand with another car so that this won't be your first car!
Good luck.
