Western Australia's road toll climbed to five this week after a fatal accident in Perth's outer east.
Police set up road blocks on Mundaring Weir Road, Mundaring, after a man was killed when his car hit a tree just before 9am on Thursday.
Commissioner Karl O'Callaghan admitted he was at a loss to come up with a new message to promote road safety.
"Some of these things are inexplicable, and that is very difficult to target strategies towards," Mr O'Callaghan said.
"So sometimes you are left thinking what do you do next, and can we go any further with this."
Thursday's crash continued a tragic few days on WA roads, which have left another four dead in three horrific crashes.
One driver was killed in a smash involving a cement truck, a road train and a car on Karnup Road in Serpentine, south of Perth, on Tuesday morning.
A father and son died in Kelleberrin, east of the capital, on Monday afternoon after their car was crushed by a semitrailer while waiting at a level crossing.
Major Crash Investigation officers charged a 45-year-old NSW man with two counts of dangerous driving causing death, and allege he was driving a prime mover with two trailers when he crashed into the Commodore.
And police are investigating a fatal crash on Monday that claimed the life of a pregnant 19-year-old.
Shona Leigh Caley and her partner, Alex Riley, 18, were travelling from Perth to their home town of Corrigin about 7.50am when their car ploughed off the Brookton Highway and struck a tree.
Mr Riley suffered minor injuries.
WA's road toll for the year now sits at 20, with 13 deaths in February.
Road statistics for 2013 released by the government showed the state's road toll of 162 was its lowest since records began in 1962.
They revealed that, while alcohol-related fatalities were down by nearly 50 per cent, 27 deaths were as a result of not wearing a seatbelt.
"2013 has been the best year to date for our road toll and for the number of alcohol-related crashes, but now is not the time to be complacent, particularly with 30 fatalities last year still linked to drink-driving," Road Safety Minister Liza Harvey said.
