The M13/40 had 42 mm of armor maximum, 6 mm minimum. Due to an underpowered engine (designed for the M11/39, which weighed two-to-three tons less than the M13.) it could only go 20 mph on road, and 8 mph cross country. The diesel engine, a 125 hp SPA 8 TM40 V8 engine, despite being underpowered, was an innovative addition, as it was less likely to break out in flames like a petrol engine when hit.
The armament was a 47 mm L/32 main gun, which at the time of the M13/40's release, was a capable anti-tank weapon, a Breda M38 machine gun in an anti-aircraft position, two Bredas mounted in the hull, and one coaxial Breda M38. The length of the M13/40 was 16 feet, 2 inches, and the width was 7 feet, 2 inches. It had four gears forward, one reverse transmission, and a bogie suspension system. The Carro Armato M13/40 was capable of carrying 104 rounds for it's main gun, over 3,000 rounds for it's machine guns, and about 50 galleons of fuel.
The M13/40 had a number of variants that were created mainly in a period of about two to three years. The first variant is M13/40 Centro Radio which had added antennas and radio equipment, but it was still more or less an M13/40. The next variant was the M14/41 which had several modifications including a new and more powerful SPA 15T engine. It also had an access door for the crew, improved air filters, and was able to carry 5.3 gallons of fuel. The M13/40 and M14/41 were later succeeded by the M15/42 which had an improved main gun and a petrol engine. The last variant of the M13/40 series was the Semovente M40, built on the Carro Armato M13/40's chassis, with a 75 mm L/18 (a short-barreled 75 mm) in the hull.
The Carro Armato M13/40 was released into service in 1940, and it mainly saw combat in the North African Campaign.  At the early stage of the war, the M13/40 was initially quite capable of dealing with the Allied tanks. It's 47 mm L/32 gun was capable of dealing with enemy cruiser tanks, although like the German medium tanks, they could not penetrate the heavily armored infantry tanks head on. It suffered from poor ergonomics. The underpowered engine gave the tank a low top speed, little better than the infantry tanks of their British opponents. Due to the Italian economy, only around 720 were produced before the end of the war. Although more than 1,000 M14/41 were produced. Some M13/40's that were captured were used by British and Australian forces against the Germans and their original owners.
- ↑ http://www.wwiivehicles.com/italy/tanks-medium/m13-40-m14-41.asp
- ↑ http://comandosupremo.com/carrom1340.html
- ↑ http://www.militaryfactory.com/armor/detail.asp?armor_id=378