Last month, Toyota recalled 133,000 2010 Prius models due to a braking issue that could cause a momentary loss of stopping power. However, in many of the claims filed with the National Highway Traffic Safety Administration, the vehicle's cruise control was brought into question, with drivers stating that they had difficulty getting the system to turn off when the brake pedal was depressed. According to Ward's Auto, 11 percent of all 2010 Prius complaints filed with NHTSA cite this issue.
Toyota is now starting to look deeper into these complaints, and believes that the majority of them are the result of driver confusion over the Dynamic Radar Cruise Control (DRCC), which is an option on the top-rung Prius V trim. In talking with Ward's, Toyota spokesperson Dave Lee says that drivers are confusing the Prius' adaptive cruise control for unintended acceleration. Lee states that when drivers use the cruise stalk to adjust vehicle speed, the rate of acceleration is much higher than when the gas pedal is pressed – it takes about one second to increase the car's speed by five miles per hour by just holding the stalk up.
What's more, reports show that drivers tend to overestimate the adaptive cruise control's effectiveness for preventing collisions, such as instances where a vehicle is stopped in the lane ahead, and that the car's owners manual typically states that both laser- and radar-based adaptive cruise systems have trouble detecting vehicles ahead of the car on curves. Two NHTSA complaints reported colliding with stationary objects when the adaptive cruise system was enabled.
Ward's says that it is unclear how many of 2010 Priuses are equipped with DRCC. Even so, the top-end V trim only makes up about eight percent of total Prius sales, so Toyota will continue to investigate these complaints before making a plan of action.