Toyota demonstrated its suite of technologies, dubbed Automated Highway Driving Assist, in a Lexus GS 450h.

The car has been retrofitted with three systems: dynamic radar cruise control, which already is in market in Lexus models and works from 0-80 mph (129 km/h), lane-trace control, also functional from 0-80 mph, and predictive and corrective human-machine interface.

The latter consists of an in-car preview of tricky highway scenarios, such as left-lane exits, and driver-monitoring cameras and sensors that result in audible and visual warnings when eyes are focused down and a hand is removed from the steering wheel.

The Toyota technology is less automated than Honda’s, reflecting the No.1 Japanese automaker’s stance that automated systems will serve to help the driver, not totally remove them from the experience of driving.

For instance, lane-trace control, supported by steering-wheel-mounted sensors, requires the driver to keep at least one hand on the wheel at all times, otherwise a warning will sound.

In a test of the AHDA suite of technologies, a forward-looking camera, grille-mounted radar and a variety of advanced, pre-production sensors help the GS 450h navigate the busy northbound Lodge Freeway in downtown Detroit.

The preview alert, a visual cue appearing on a large, non-production center screen in the GS 450h, warns the car’s driver that an upcoming freeway exit is ahead on the left.

“The benefit is the driver avoided any last-second maneuvers, so any risk of collision is also reduced,” says Toyota Senior Scientist Rohit Pandita, who works in the automaker’s Ann Arbor, MI, tech center’s Integrated Vehicles Systems unit.

The preview technology uses the forward camera in conjunction with GPS and an enhanced map to determine where a vehicle is relative to other lanes, he says.

Moments later, when taking the exit for the eastbound Davison Freeway, a warning sounds to let the driver know the lane soon will exit onto Woodward Ave.

An “unsupported scene view” warning appears when approaching the exit for southbound I-75 from the Davison, as during testing two weeks ago faded lane lines were recorded.

They’ve since been painted, and Pandita says the system will learn the new lane lines. However, in this demonstration, the driver is warned to stay alert.

In another scenario on southbound I-75, the driver looks down from the road and takes his hands off the wheel, causing the car to chime urgently for him to re-engage.

“(The chimes) get louder and more annoying,” Pandita says, adding Toyota is still deciding whether or not lane-trace control in production will disengage should the driver not return attention to the road.

As I-375 ends and the GS approaches Jefferson Ave., an “end of highway” preview warns the driver must take control as the system support is ending.