I've done this. I don't start the trip till we've had a little 'come to Jesus' talk. I ask if they have trouble getting a car, if they say yes, I explain why. If they say no, I express surprise and point out their rating. If, during our talk, they start going off the rail, I decline the ride with no charge. If they do not go off the rails, I start the trip and during the trip give some tips on how to get it up, with 'tips' being the operative word.