Drivers are putting too much trust in their vehicles’ driver-assist features, which may lead to dangerous situations, according to the Insurance Institute for Highway Safety (IIHS).

The organization, which researches vehicle safety, released a study Tuesday finding that 53% of General Motors’ Super Cruise users, 42% of Tesla Autopilot users and 12% of Nissan’s ProPilot Assist users were comfortable letting the system drive the vehicle without them watching what was happening on the road. Some even described being comfortable letting the vehicle drive during inclement weather and in parking lots.

These systems are all driver-assist features that combine adaptive cruise control and lane-keeping systems, primarily to keep a car in a lane and following traffic on the highway. They all require an attentive human driver to monitor the road and take full control when called for. The IIHS did not survey owners of other systems with similar capabilities, like Ford’s BlueCruise.