Dear Tom and Ray: I hope you can help me. My rear passenger side air bag deployed, along with the passenger side mid bag and the window shield. There was no impact. I was moving at 35-40 mph on a smooth road with no potholes. I took the car to the dealer to get the problem fixed. They said it was not their problem and that I must have hit something. They saw a mark on the wheel and said I set off the bag when I hit a curb. OK ... so I hit a curb, but it was two weeks before the bag exploded. I don't think air bags have that kind of delayed reaction. So the question is, Where do I go to get the dealer to do the right thing? What federal or state agency should I report this to? My insurance company knows about it, and is trying to help. However, I want to be sure the dealer fixes what it should fix. What do I do to hold their feet to the fire? Please help me. -- Eileen P.S.: It is a Mercedes E350, and I have found another case just like this online.

RAY: Ah, yes. The old "Air Bag Surprise." Very exciting!

TOM: We've found that dealers and manufacturers get very squirrely when air bags go off when they're not supposed to.

RAY: It's not just Mercedes, Eileen. They're all deathly afraid of admitting liability in cases like this. You can imagine that if an air bag goes off without reason, it can CAUSE an accident rather than prevent one.

TOM: And you can imagine what a horrible public-relations disaster it would be if word got out that some manufacturer's air bags were popping off on their own. People would flee from the showrooms.

RAY: But once in a blue moon, air bags do deploy on their own. During the past 20 years or so, 43 vehicles have been recalled for "surprise" air-bag deployment.

TOM: But in our experience, until a recall is actually issued, manufacturers tend to play dumb or blame the customer when this happens. So I have a sad feeling that you're not going to get real satisfaction. I hope I'm wrong, but that's been the pattern we've seen.

RAY: So if they continue to insist that you had an accident when you clearly didn't, and no one higher up in the Mercedes hierarchy will help you, then you have to wait for the feds to force them to act. You can assist in that process by filing a complaint with the National Highway Traffic Safety Administration, or NHTSA.

TOM: That's the federal agency that monitors safety complaints about cars. If it sees a pattern of complaints about a certain vehicle, it'll open up an investigation. And if the investigation turns up evidence of a defect, it can issue a recall.

RAY: Meanwhile, I'd insist (or get your insurance company to insist) that your dealer replace not only the deployed air bags, but also the car's air-bag control unit, which would be my first guess as to the source of the problem. But it's just a guess.

TOM: And file your report with NHTSA at www.safercar.gov, or by calling NHTSA Vehicle Safety Hotline at 888-327-4236. Good luck.