The M-18 Tank Destroyer, nicknamed the "Hellcat" by the Soldiers who crewed them, earned a reputation of being one of the most effective tank killers in the Army during World War II. Built by Buick Motors Division, the M-18 was capable of reaching sustained road speeds of 55 to 60 mph. Hellcats could outrun the German Panzers, firing several rounds before the enemy could traverse their turret to engage the tank destroyer. The M-18 also acted as an infantry support weapon and a mid-range mobile artillery piece, depending on the mission. The weapon did have a few weaknessess, however. It had an open turret which exposed the crew to enemy fire from aircraft, it sacrificed some armor in order to gain more speed, and it featured a smaller gasoline engine instead of a more powerful diesel. The 76mm main gun fired an effective tank-killing round, but was seldom able to kill the the heavily armored Panzers in one shot. The gun fired both armor piercing and high explosive rounds.