Engineer's Investigation

(1) P offers an engineer to give her opinion that the steering wheel of P's car was defective prior to the accident. She bases her opinion on her post-accident examination of the wreck and on the statement of the driver, reported to the engineer, that the auto lost its steering control before it crashed. How should the trial judge decide whether the engineer's opinion is admissible?

(2) Could the engineer state her opinion without revealing the information on which she based it? If so, how would opposing counsel probe to find out what the basis of the opinion was and what would happen if and when the arguably impermissible basis for the opinion emerged?

(3) Would the situation be materially different if the case were criminal instead of civil?