My wife was driving our Hyundai Tucson on the city street at about 35 mph. She signaled left to get into a turning lane. The turning lane has two lanes and is very long. She got into the turning lane and the traffic in front of her stopped. The car's collision avoidance system activated and slammed on the brakes even though the vehicle was not very close to the cars in front of her. As a result, a vehicle behind her rear ended her causing over $9,000 in damage. This car has done this before on the highway and city street. The collision sensitivity setting was on normal and had been since we got the car and until the accident. I had also been driving the car when the collision avoidance activated. The problem with this car is that it only knows to slam on the brakes and results in getting rear ended. It does not gradually apply the brakes even when the car in front is not very close and locking up the brakes is not necessary and is actually unsafe as shown when my wife was in a rear collision accident. This is a major safety problem and needs to be looked into.