One thing ISIL (Islamic State in Iraq and the Levant) took advantage of in 2014, when they captured over a thousand of Iraqi Army vehicles, was to use the several dozen (at least) armored trucks they had captured as combat vehicles. These were American 6x6 Medium Tactical Vehicle Replacement (MTVR) vehicles that weigh over 14 tons. The U.S. Marine Corps bought over 10,000 between 2005 and 2011 and one of the export customers was Iraq. The MTVRs in Iraq often had the optional armor kit, which made the truck bullet and shell fragment proof. The armor kit included adding a machine-gun mount and bullet proof glass as well as strengthening the suspension and other mechanical components to handle the several tons of weight. In some respects armored MTVRs were more useful to ISIL than MRAPs (bomb proof armored trucks) because the MTVRs required less fuel and were faster on road and more stable off-road.
ISIL also copied the improvised truck armor American troops used after 2003 for several years before MRAPS and trucks with factory installed armor arrived. Many of these armored trucks were simply given to the Iraqi security forces as American troops left as the U.S. military didn’t need all of them. ISIL certainly found them useful for moving quickly about on roads (paved or otherwise) and making surprise attacks on Iraqi forces. The ISIL armored trucks were vulnerable to light anti-armor weapons like RPGs and Western equivalents. Hellfire missiles would also knock them out but because MTVRs had additional armor for the drivers compartment, putting a Hellfire into the armored cargo area would probably disable the vehicle and destroy everything in the cargo compartment, but the two or three in the drivers cab would probably survive.
ISIL also used these armored trucks for suicide truck bombs. This way the suicide bomber could literally barge into a heavily guarded target (usually a walled compound with only a few vehicle access points) and detonate tons of explosives once inside. This was becoming increasingly difficult as local security forces adopted defensive measures developed by the Americans and Israelis. In some parts of Syria and Iraq warplanes were told to attack any of these armored trucks they saw moving, especially if they were painted in the garish color schemes ISIL favored.