I don't know your mechanic from Adam, so this may not apply. But it's been my experience that when a mechanic starts telling you to get another car because he can't fix it that usually means it's time for a new mechanic. I've never had a good mechanic tell me I need a new car. Instead I've had 'em tell me it's gonna cost more to fix than the book value of the car then leave it up to me to decide. That's my $.02 worth.
