You probably do not really think about whether those scary guys who do all the heavy-duty 3D stuff at the end of the office do everything from scratch.
Start worrying if they do because it is not as if building a late-model Mondeo for every new perspective can be done overnight. In fact, there are 3Dmodel databases all over the place which offer practically everything from ants to the latest business jet to well-known buildings. I know of nearly 40 of these databases. Some are maintained by universities, others by software firms and yet others by commercial organisations. The site where they are reported is www.agocg.ac.uk/reports/virtual/36/report36. htm.
OK, it is dated 1997 and you'll have to use a search engine to check out the databases it discusses, but it does provide a helpful summary for each of them and it is the most comprehensive guide on the net - until you tell me otherwise.