A book that I am currently reading that I have found tremendously helpful and thought provoking is The Four Steps to the Epiphany by Steven Gary Blank. Most customers don't miss product development, they miss CUSTOMER development.
Disclosure: I am developer, not a marketing used car salesman.
Disclosure: I am developer, not a marketing used car salesman.
http://www.shelfari.com/books/1344861/The-Four-Steps-to-the-...