BAGHDAD, Iraq, Dec. 8 — They were a father and son shopping for a car for the young man, a family ritual as common as any in the United States. It was unfolding on a recent evening here, though, to the cadence of distant gunfire and explosions. Aadel Kadhem, 43, and his 23-year-old son, Mohammed, walked around a pair of black BMW's, opening the doors, staring through the windows. Aadel Kadhem paints automobiles for a living, and his income has risen tenfold since the fall of Saddam Hussein's government, he said, allowing him to squirrel away $3,000 for a car...