WASHINGTON, Oct 11 (Reuters) - Drivers using advanced driver assistance systems like Tesla (TSLA.O) Autopilot or General Motors (GM.N) Super Cruise often treat their vehicles as fully self-driving despite warnings, a new study has found.The Insurance Institute for Highway Safety (IIHS), an industry funded group that prods automakers to make safer vehicles, said on Tuesday a survey found regular users of Super Cruise, Nissan/Infiniti (7201.T) ProPILOT Assist and Tesla Autopilot "said they were more likely to perform non-driving-related activities like eating or texting while using their partial automation systems than while driving unassisted."Register now for FREE unlimited access to Reuters.comAbout 40% of users of Autopilot and Super Cruise - two systems with lockout features for failing to pay attention - reported systems had at some point switched off while they were driving and would not reactivate.Since 2016, the NHTSA has opened 37 special investigations involving 18 deaths in crashes involving Tesla vehicles and where systems like Autopilot were suspected of use.IIHS said advertisements for Super Cruise focus on hands-free capabilities while Autopilot evokes the name used in passenger airplanes and "implies Tesla’s system is more capable than it really is.""