Almost half of all crashes on Australian roads could be averted if drivers simply paid more attention, according to one insurer's Annual Crash Index.

Is says 30% of crash-related claims result from front-to-rear collisions, carrying an average repair bill of $2,700.

The survey shows basic inattention contributes to 44% of all car collisions, followed by speeding (17%), fatigue (11%), and alcohol (9%).

Almost one in six collisions (18%) involves stationary objects such as a pole or parked car. These crashes on average cost over $1,800.

Crash statistics aren't helped by the 34% of drivers who admit to driving despite knowing the breath alcohol limit is above .05.