It was powered by a water cooled Hercules model JXD gasoline engine and it could move at speeds of around 88.5 km/h. The Greyhound also had a crew of four and entered service in 1943. It was armed with a 37 mm main turret, which was not powerful enough to allow it to combat other tanks as a tank destroyer, as was originally intended.
Along with the 37mm main gun, a .30 M1919 was positioned in the turret and a .50 M2 could be mounted on top. The M8's main strength was its speed; it could outrun most attacks and enemy fire. The total weight of the M8 was about 7,400 kilograms and while its total length was about five meters. The transmission also had 4 forward speeds and 1 reverse.
The M8 Greyhound had some variants that looked fairly similar to the original, but each variant served its own purpose and had special modifications. One notable variant was the M20 Armored Utility Car, which could be used as a command car or to carry cargo. It had no 37 mm gun. Instead, the main armament was a .50 M2 mounted where the original turret would have been.
Another variant was the M8E1 Greyhound with only one major modification: the suspension. Very little of these vehicles were produced. The last variant of the M8 Greyhound was the prototype T69 Multiple Gun Motor Carriage. It essentially featured four .50 M2 MGs in place of the 37 mm gun and it was meant to serve an anti-aircraft role. It never reached production or service.
The M8 was originally developed for the Tank Destroyer Force, but the shortcoming of the 37 mm gun was well established before it was fielded The Cavalry then adopted it as an improvement over the unarmored jeeps then in use. The M8 was sent to both the European Theater and the Pacific Theater. The M8 was particularly useful when fighting weaker-armored Japanese tanks. It also operated well in the European Theater as it was able to outrun most tanks. The durability of the M8 played a key role in its ability to fight in most environments. It was also used by British forces, who found it to be underarmed.