Swerve the car from side to side - as tired drivers are prone to do - and it will emit another warning signal.
Even if you're sitting in heavy traffic and the car in front moves off without you noticing, EyeSight will let out a little beep.
It's clever stuff. Best of all, Subaru claims that some insurers (including its partner Allianz) have recognised the safety benefits of EyeSight by reducing premiums by up to 20 per cent on cars fitted with the device.
Subaru's system also includes an "adaptive cruise control" which allows the driver to choose a set distance between from the vehicle in front while on the open road - automatically accelerating or braking to maintain the appropriate gap.
Some of these distance-control cruise systems have their flaws - we've driven versions which are easily spooked by vehicles slowing or diving into the lane in front - but the Subaru version seems particularly intuitive.
Should the vehicle ahead perform a sudden stop, though, EyeSight quickly engages the brakes.
We tested EyeSight in the refreshed Subaru Outback wagon - not one of the newer models in the Japanese maker's range that is to be launched in New Zealand next month.
It helped alert us to a tricky situation before an object - a darkly dressed pedestrian on an unlit road - was visible to the naked eye.
While the regular beeps from the system can be irritating, it does what it is designed to do - keep the driver alert and aware of any hazards.
When an obstacle is detected, it uses brake assist to optimise braking efficiency. Subaru says the system will stop the car completely when an obstacle is detected at speeds of up to 30km/h.
A pre-collision throttle management function will, if the driver accidentally applies full throttle with a barrier or large obstruction in the way, limit the car's acceleration. It also operates if a driver accidentally selects "Drive" instead of "Reverse".
EyeSight is part of a mid-model update for the Outback and is available in the 3.6R Premium model in Australia for A$57,490 ($73,670).
Cutting-edge motoring technology proves a winner
Subaru's EyeSight driver assist system has won a top Japanese government science and technology award.
The five Fuji Heavy Industries (FHI) engineers who developed EyeSight received the prize for Science and Technology 2012, Development Category, from Japan's Minister of Education, Culture, Sports, Science and Technology.
The awards honour those who have made noteworthy contributions either to the research and development of science and technology, or to its public understanding.
It is the first time FHI has won the award.
The FHI representatives recognised in the award all work in the Third Vehicle Research and Experiment Department, Subaru Engineering Division.
Since its introduction in Japan, this user-friendly system has been highly praised for a good balance between its affordable pricing and excellent utility.
Sales of EyeSight models in Japan have accounted for more than 80 per cent of the total of some Subaru model ranges.
- AAP
