The 2020 Kia Telluride and Hyundai Pallisade are the first Kia/Hyundai vehicles to offer Highway Drive Assist, a driver assistance feature that is part of the Kia DRIVEWiSE system and the Hyundai SmartSense system. The information provided about the feature is not very clear. From the Kia website:
Highway Driving Assist (HDA)
Highway Driving Assist (HDA) is a driving convenience and safety system that reduces driver burden on highways and motorways by controlling the vehicle’s steering, acceleration and deceleration functions to maintain the speed set by the driver, keep a safe distance from the vehicle directly ahead, and keep the vehicle in the center of its current lane.
HDA uses navigational information to determine whether the vehicle is on a highway or motorway. When the vehicle is on a highway or motorway, HDA maintains the speed set by the driver or the speed limit of the highway or motorway. At the same time, it considers the lane information collected through its front view camera, and relative position and speed of the vehicle directly ahead computed using its front view camera and front radar, to control steering, acceleration and deceleration while keeping a safe distance from the vehicle ahead.
So, I would break features down to the following: adaptive cruise control (acceleration/braking), lane centering (steering), and length of time before requiring manual intervention (resume from a stop in traffic, or replace hands on the steering wheel).
The explanation regarding adaptive cruise control features seem pretty clear. Basically, it is like every other adaptive cruise control with the extra ability to maintain your speed at the posted speed limits on highways. I don’t find that particularly useful as traffic is typically 5-10 mph over the speed limit near me, unless there is traffic slowing everyone down. Maintaining at the speed limit would possibly be more of a hazard compared to driving at the speed of surrounding cars.
Lane centering is a little less clear to me. Kia/Hyundai refers to their lane centering steering as Lane Follow Assist; however, I’m not sure how Lane Follow Assist works (is it based just on lane markings or does it also track the position of the vehicle in front to follow) and whether it is the same with Highway Drive Assist. From the same website as above, but no mention of tracking the position of the vehicle in front:
Lane Following Assist (LFA) is a driving convenience and safety system that reduces driver burden by controlling the steering function of the vehicle to keep it moving along the center of its current lane.
LFA identifies the vehicle’s current lane and the lane boundaries using its front view camera, then automatically steers the vehicle to keep it in the middle of the lane whenever it detects that the vehicle is unintentionally veering out of the lane.
There is also mention in this forum post that Highway Drive assist likely allows for a longer period of stopping in traffic before it disengages, compared to standard adaptive cruise control. For example, typically, after the car is stopped in traffic for 3 seconds, adaptive cruise control requires you to resume driving manually either by hitting the gas pedal or by hitting the resume button for cruise control. Highway Drive Assist, however, allows for a much longer period of being stopped before requiring a manual resume action.
Overall reviews for the Kia/Hyundai lane follow assist have been very positive. Most people say it works better than competing systems short of Tesla, and even then it sounds like it is not far behind in many circumstances. Generally, it does a good job keeping the car centered and following moderate curves in the road. However, there are several reports that on sharper turns the car does get close to the lane markers. Based on reviews, it seems the lane follow assist is the same whether highway drive assist is engaged or not.
The auto speed adjustment feature highway drive assist adds seems pretty useless and reviews seem to agree. The main useful advantage of Highway Drive Assist people have reported (which is not mentioned by Hyundai/Kia that I can find) is the automatically resume from a stop after longer than 3 second delays. For people who want that feature, you need the Highway Drive Assist. I’m not able to tell anything else that would be different between standard Lane Follow Assist / Adaptive Cruise Control and the Highway Drive Assist feature.
Other reviews also noted that the Kia/Hyundai lane centering seems to stay active for quite a while before disengaging if hands are not detected on the wheel.