Stock downloadable 3ds Max objects

I was wondering if there is a place where one could get some already built cars or objects and such for compositing practice? I thought I was reading a thread a while back of a scene someone had designed in 3d and did a matte painting for but then brought in a stock 3d car to put in their scene without having to sit and model it. Any websites or anything to get this kind of stuff? Thanks

 

Great stuff ATD thanks alot.