The latest bloodshed comes amid a surge in violence that left more than 1,000 people dead last month, the worst such figure in nearly six years, as security forces grapple with near-daily attacks and protracted battles with anti-government fighters.
Foreign leaders have urged the Shiite-led government to do more to reach out to the disaffected Sunni Arab minority in a bid to undercut support for militants but with parliamentary polls looming in less than three months, Iraqi premier Nuri al-Maliki has taken a hard line.
In and around the capital today, four car bombs killed 12 people while authorities said they found the dumped bodies of three men and a woman. All were shot in the head and they appear to have been tortured.
Seven people were killed in two separate car bombs -- one of which was detonated by a suicide attacker -- in the town of Mahmudiyah, just south of the capital, while five others were killed by vehicles rigged with explosives in the Baghdad neighbourhoods of Baladiyat and Hurriyah.
Violence has surged across Iraq in recent months, with more than 1,000 people killed nationwide last month, the highest such figure since April 2008, according to government data.
Shootings have largely targeted security forces and civil servants, while bombings have ripped through both Sunni and Shiite areas, striking markets, commercial streets, cafes and other areas where civilians congregate.