I am in the process of creating a new service that is part productivity tool, part recommendation engine. Think of it as a task-list on steroids: one with a recommender system that listens/analyzes the "tasks" you and friends create and accomplish. Though there are a couple more wrinkles, this gives the general context.
Initial testing suggests that the data needed by recommendation component takes the typical user around 3 min to enter. The user experience is significantly improved by the recommendations made.
1. Any suggestions to keep the user engaged through this 3 min bootstrap? Anything that's worked particularly well for you?
2. I think some other applications have a similar bootstrap-- how do you get users to enter details about the car they want to buy, for instance. What are your usual abandonment rates?
Do you have to take all of this info during signup? Is it possible to give them an account without this info, then get them to add more piece by piece?
Some game mechanics might help - e.g. showing them that their profile is 10% complete, and that completing X will add 10%, Y will add 15% and so on.
Wrt your car question - something I see on a lot of sites is 'faceted navigation' - show them a load of results, but give them links to click in order to narrow down the info. When they click a link, you learn a bit about them (e.g. they want a blue car).