The driver in such a situation might not realize the deep criminal risk s/he might be in. Cops love getting confessions by saying: "I know you were just the getaway driver. Do you want me to tell the prosecutor you confirmed that?"
None of my comments on AVVO's website constitute legal advice. It is only food for thought for matters to address with a qualified laywer. My website's disclaimer page at http://katzjustice.com/disclaimer.htm applies to all my answers on AVVO.com .