The bloodshed, in which more than 6,000 people have been killed this year, is the worst prolonged stretch of unrest since 2008 and comes just months before a general election, forcing Baghdad to appeal for international help in battling militants.
Although there have been no claims of responsibility for much of the unrest, officials see the hand of a resurgent Al-Qaeda emboldened by the civil war raging in neighbouring Syria.
Babil province, south of Baghdad, suffered the lion's share of the car bombs, as a half-dozen struck provincial capital Hilla and nearby towns, killing six people and wounding dozens more.
Another vehicle rigged with explosives targeted Salaheddin provincial police chief Major General Juma al-Dulaimi. It killed three civilians and wounded two others.
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A suicide car bombing at a police checkpoint near Samarra, also in Salaheddin, killed three police and wounded three more.
Two more car bombs in predominantly-Sunni Salaheddin and two others in Wasit, a mostly Shiite province south of Baghdad, killed three people and wounded 15.
Also in Salaheddin, militants who set up a fake checkpoint gunned down six people -- a senior official in Iraq's identity card department and his wife, two policemen and two other civilians.
Meanwhile in Baghdad, a roadside bomb targeting a patrol of Sahwa anti-Al-Qaeda-militiamen killed two people, one of them a Sahwa fighter, and two other bombs elsewhere in the capital killed four more.
Sunni militants view them as traitors and frequently target them. Also today, shootings in the northern city of Mosul killed four people, including two members of the Yazidi religious sect.