Very smart and well-researched process:
Submit resume through an Analyst Development Program online.
Phone screening interview.
and/or School campus interview if you're a junior/senior at a college they hire from.
Corporate Campus interview.
Hiring decision (about 90% reduction at each step)
The phone screening is mostly a goodness of fit for the roles you could be considered for. They suggested I should be a Data Analyst given my background in engineering (but really because they don't have enough DAs) but I prefered Operations, so I interviewed for that (probably should have gone with DA given my personality)
School and Corporate campus interviews are the same, consisting of a mix of Case and Behavioral interview sections. They should still give an example case and some example behavioral questions because they want to test how you think, not how familiar you are with interview techniques. But in case they don't, just have a few good "tell me about a time when..." stories that you can apply for different questions. For Case interviews, write equations down and edit them as the follow-up questions get more complex. "Are you sure?" isn't always a hint that you're missing something. Each section is done by a different interviewer and scored so that individual rapport bias will be less important. Also, no one wears coats or ties at Capital One except for interviewees. I skipped the tie and was fine.
I believe they got rid of this, but there used to be an online screening test for reading comprehension and business math. The reading comprehension would try to trip you up because you could only use knowledge from the presented material, so even if you know the speed of sound is slower than the speed of light, the correct answer is "I don't know" if you couldn't find it in the reading. The business math was algebra-level and some statistics with some business knowledge. Plenty of practice questions available.
I daresay the whole process was fun.