This is a problem I have been considering for some time (years). A substantial amount of my work involves modeling/ visualising automobile events, (our end user being a car manufacturer). This obviously requires many vehicle & people/crowd models. For the most part I use 2D 'face-me' component people... not too bad. For cars I either use a suggestion of a car shape in the form of an inflated bubble form (Artisan assisted) or if I need to be specific I can usually plant a photographic image into the visual post production. Its not ideal, but it works.
I am now producing more animated work including fly-throughs of the larger events... making the above photographic solutions unsuitable.
What I am now looking for is a suitable source for people models (FormFonts seems the best option) & a supplier for low poly car models. Here's the tricky bit - these need to be consistent quality, specific manufacturer & specific model/year. So warehouse isn't really going to help here - its not going to work if one model is beautifully detailed while the one next to it isn't.
The level of modeling required has proved beyond my current skills & I have not yet found a supplier on-line. My client has intimated that he might invest in this so it opens the option to us commissioning these models. I know there are many impressive vehicle modelers out there so is you are interested, I'd appreciate if you would contact me.
many thanks