4. WWI Tank (UK)

First produced in 1917. Top speed: 4 mph. Range: 22 miles. Its Daimler six-cylinder engine gives a power-to-weight ratio of 3.3 horsepower per ton. Armor thickness: 6-12 millimeters. Primary armament: two 6-pounder guns.

The WWI tank did have thin armor — but it was the only armored vehicle in existence, so it scores well in this category, as it does on mobility and firepower. But it was not an easy machine to manufacture, being very much a high-tech product in its day, so it scores below average in this category. However, its fear factor was massive — nothing like it had ever been seen before — earning it a respectable fourth place on the list.