While driving abut 30 mph, the car beeped twice and the seat belts snapped very tight and the seats went erect for no reason. The car senses a possible crash when nothing is imminent. This is physically and mentally very frightening and could cause a driver to have a collision if it occurs in traffic. This has happened twice and Mercedes says there is nothing they can find that would cause this. So, nothing has been done to correct the problem. One more episode and I will have to file a Lemon Law complaint if the dealer cannot correct the issue.