The M8 Greyhound was a 6x6 armored car produced by the Ford Motor Company during the Second World War. It was used by the U.S. and British troops in Europe and the Far East until the end of the war. The vehicle was widely exported and as of 2002 still remains in service in some third world countries.

In July 1941, the Ordnance department initiated a development of a new fast tank destroyer to replace the M6 37 mm Gun Motor Carriage, which was essentially a 3/4 ton truck with a 37 mm gun installed in the rear bed. The requirement was to a 6x4 wheeled vehicles armed with a 37 mm gun and a coaxial machine gun mounted in a turret. Its glacis armor was supposed to withstand a .50 cal. machine gun fire and side armor a .30 cal. machine gun fire. Prototypes were submited by Studebaker (T21), Ford (T22) and Chrysler (T23), all of them similar in design and appearance. In April 1942 a modified version of the T22 was selected. By then it was clear that the 37 mm gun would not be effective against the front armour of German tanks so the new armored car, designated M8 Light Armored Car and named Greyhound by the British due to its high speed but thin armor, took on reconnaissance role instead. Contract issues and minor design improvements delayed serial production until March 1943.

The M8 was fitted with a 37mm M6 gun (aimed by M70D telescopic sight) and a coaxially mounted .30 Browning machine gun in an open-topped turret and an M2 machine gun on a ring or pintle mount for anti-aircraft use. The crew of four comprised the commander, gunner/loader, driver, and radio operator (who could also act as a driver). The driver and radio operator were seated in the forward section of the hull, while the commander and gunner rode in the turret, commander in the right side. The vehicle carried 80 37 mm rounds (vehicles with a second radio installed could carry less, sometimes only 16 rounds), with 1500 .30 cal and 400 rounds .50 for the machine guns. In addition it carried 16 hand grenades, 4 smoke pots (M1 or M2) 6 landmines (Anti-tank and HE types) and M1 Carbines for the crew.

The armor ranged from 3mm under the hull, to 19mm in the front hull and turret. The Greyhound was powered by a Hercules Model JXD in-line 6-cylinder 320 cu.in. gasoline engine giving it a top speed of 56 mph on-road, 30 mph off-road. With a 59 gallon tank, and an average fuel consumption of 7.5 mpg it could manage an average range of 400 miles.

Production of the M8 ended in June 1945. 8,634 units had been built, not including the M20 Armored Utility Car.

The M8 first saw action in Italy in 1943 and was used by the US Army both in Europe and in the Far East. In the latter theater it was occasionally employed in its original tank destroyer role as most of the Japanese armor was vulnerable to its 37 mm gun. Over 1000 were supplied via lend-lease channels to Britain, France and Brazil. The vehicle was considered fast, sufficiently reliable (after some techical problems were solved) and armed ard armored well enough for reconnaissance missions. However cavalry units criticized its off-road performance. In the mountainous terrain of Italy and in the deep mud and snow of North European winter the Greyhound was more or less restricted to roads, which reduced its value as a reconnaissance vehicle. It was also vulnerable to landmines. The British sometimes placed sandbags on the floor inside to make up for the lack of armour underneath. Other problem was that commanders often used their reconnaissance squadrons for fire support missions, for which thinly armored M8 was ill-suited.

US Army started to look for a replacement for the Greyhound as early as in 1943. Two prototypes, Studebaker T27 and Chevrolet T28 were finished in summer 1944. Both were found superior to the M8, but it was decided that at this stage of the war ther is no more need for a new armored car.

After the war, the M8 was used for the occupation duty, saw combat in the Korean War and was retired by the US Army shortly thereafter. A number of Greyhounds were given to the US Police and served there until 1990s. France continued to use the M8 until the First Indochina War. Many vehicles formerly used by the US, Britain and France were exported to NATO allies and third world countries. As of 2002, some still remain in service in Africa and South America.

• M20 Armored Utility Car

The M20 Armored Utility Car, also known as the M20 Scout Car, was a Greyhound with the turret removed. This was replaced with a low, armored open-topped superstructure and a ring mount for a .50 caliber AA M2 heavy machine gun. A bazooka was provided for the crew to compensate for its lack of anti-armor weaponry. The M20 was primarily used as a command vehicle and for forward reconnaissance, but many vehicles also served as APC's and cargo carriers. It offered high speed and excellent mobility, along with a degree of protection against small arms fire and shrapnel. When employed in the command and control role, the M20 was fitted with additional radio equipment.

Originally designated the M10 Armored Utility Car, it was changed to the M20 to avoid confusion with the M10 Wolverine tank destroyer. 3,680 M20's were built by Ford during its 2 years in production (1943-1944).

• T69 Multiple Gun Motor Carriage

In late 1943 an anti-aircraft variant of the M8 was tested. The vehicle was armed with four .50 cal. machine guns in a turret developed by Maxson Corp.. The Antiaircraft Board felt that the vehicle was inferior to the M16 MGMC and the project was closed.

• M8 TOW Tank Destroyer

M8 upgraded by US company NAPCO. The main gun was replaced by an .50 cal machine gun and a BGM-71 TOW launcher was installed above the turret. Some upgraded vehicles were used by Colombia.

• M8/M20 with H-90 turret

A French upgrade, using the turret of the Panhard AML 90 armored car.

• CRR Brasiliero

A Brazilian upgrade. The middle axle was removed and a new engine (Mercedes-Benz OM-321) installed. Didn't reach production.