Pulling results from other site

To start with

[collymellon]

Hope all is well,

I'm planning a large motor site - but due the large market of online motor adverts allready taken over here in the UK (well prob anywhere) I was thinking a creating a large site which allows users to search for a car from all the major databases. Questions:

1. Can I do this? (use other sites car adverts)
2. How would I go about fishing in there database so to speak when a user performs a search for a particular car?

I know this is possible due to a number of other search sites that when you search it brings up results from examplesite1, examplesite2 etc.. with a link direct to that site. This would help the larger sites and give me traffic (no pun intended :) through my site.

Any remarks greatly appreciated