Donata.com writes about auto advertisers shifting budget from tv and print ads to the internet. He’s predicting a new trend in online advertising, away from search context ads (Google) and an unstructured database (Craigslist), and toward structured, decentralized, XML-based ads. In this model, each dealer would post their list of available cars, with price and options. Now, there are already a plenty of centralized aggregator services. Froogle can find you deals on desk lamps and rain boots. If Froogle let users subscribe to a search by RSS, that would be a long way toward the vision.