That helps a lot.
Your file is thin enough that another card wouldn't hurt. I'd grab a card (maybe two) once you have the car loan. Then figure on gardening (not applying for anything or taking any hard inquiries) for a year. Because they're soft pulls, you can ahead and ask for limit increases on your Capital One card during your gardening period.
You're in great shape for most credit card products out there. I think either AMEX or Discover would be a great choice for a second card. I think a third card (whether it's acquired now or in the future) should be a Mastercard or Visa.
