Officers guarding the police station in the capital's southern Dora neighbourhood opened fire on the vehicle as it sped towards them and exploded, a police official said on Friday.
Baghdad's Dora neighbourhood has become a flashpoint in recent days, with several street battles between fighters and Iraqi National Guard troops and the killing of government officials.
On 10 January, attackers shot dead Baghdad's deputy police chief, Brigadier Amir Ali Nayif, and his son, also a police officer, in the Dora district.
Iraqi police and soldiers have been repeatedly targeted by fighters ahead of the country's elections on Sunday.
Marine base attacked
Meanwhile, fighters shelled a US marine base south of Baghdad on Friday, injuring three American soldiers and three civilians, the military said.
Mortar shells exploded inside Camp Kalsu, the main base of the 24th Marine Expeditionary Unit. One marine, two soldiers and three civilians were injured, the military said. There was no immediate word on any deaths in the attack.
Fighters are pursuing a
campaign to disrupt the polls
In a separate development, an Iraqi policeman was killed and two civilians wounded in a host of attacks on buildings to be used as voting stations around Kirkuk, 250km north of the capital.
The policeman was shot dead by attackers as he stood guard at one voting station in the east of the city, police said.
An Iraqi soldier was killed and another wounded when their
patrol vehicle went over a mine near Samarra, north of Baghdad, police said.
Also, one man was wounded in an attack on another polling station at al-Dur and another civilian was injured in a mortar attack on a voting centre in Tikrit.
Dozens of voting stations have been attacked by fighters who have put up posters and handed out leaflets warning Iraqis not to vote.