The M3A1 Scout Car was used by cavalry units of the US Army in its intended cavalry role during the North African Campaign and the invasion of Sicily, being employed for reconnaissance, screening and as an armored command vehicle.
The M3A1 was fast and reliable, making it popular with its crews.
It was considered a major disappointment in US Army service, primarily due to its poor offroad performance, but also its lack of overhead protection.
Cavalry units were forced to supliment it with M2 and M3 Half-tracks.

Throughout 1943, most US Army units replaced the M3A1 with the M8 armored car and the similar M20 Utility Car, although the M3A1 was retained for rear area security and convoy escort duties.
A small number of M3A1s were employed in Normandy.
A few M3A1s were used by the US Marine Corps in the Pacific theater, but none saw combat.

General George Patton used an M3A1 Scout Car as a command vehicle, modified with additional armor and a raised fighting compartment.

A total of 11,401 M3A1 Scout Cars were allocated for supply to US allies under lend-lease, 6,987 were supplied to the British Commonwealth, 3,310 to the Soviet Union and 104 to the Chinese Nationalist Army.
Some were also supplied to Free Belgian, Free French, Czechoslovak and Polish units.

In British Commonwealth service, the White Scout Car was regarded more as an armored truck, reflected in the designation Truck, 15cwt, 4x4, Armoured Personnel, and was used in a variety of secondary roles, being issued to engineer, artillery (as an observation vehicle for field artillery observers) medical (as a protected ambulance) and signals units; within the Royal Armoured Corps’ Tank and Armoured Car Regiments it usually served in Squadron or Regimental  headquarters.
It was used by British Commonwealth forces in every theatre they fought in except Burma.

In Red Army service, the M3A1 was used as an armored personnel carrier by brigade and corps reconnaissance units and motorcycle battalions and regiments, operating alongside the BA-64.
The M3A1 was also used as an armored command vehicle and a gun tractor for the ZIS-3 76-mm field gun, although the towing hitch proved to be unreliable, the M3A1 remained in widespread service throughout the war.

The Chinese Nationalist Army received M3A1 Scout Cars from 1942 and used them throughout the Second Sino-Japanese War and the Chinese Civil War.

After the war, many vehicles were sold, mostly to Asian and Latin American countries while they remained in Soviet service until 1947.

A few vehicles were used by Israel in the 1948 Arab–Israeli War.
At least one Israeli M3A1 was modified with top armor and a revolving turret.
France employed its M3A1s in the First Indochina War  and the Algerian War.

By late 1990, the only country with the M3A1s remaining in service was the Dominican Republic.
The M3A1 Scout Car was used by cavalry units of the US Army in its intended cavalry role during the North African Campaign and the invasion of Sicily, being employed for reconnaissance, screening and as an armored command vehicle. The M3A1 was fast and reliable, making it popular with its crews. It was considered a major disappointment in US Army service, primarily due to its poor offroad performance, but also its lack of overhead protection. Cavalry units were forced to supliment it with M2 and M3 Half-tracks.
Throughout 1943, most US Army units replaced the M3A1 with the M8 armored car and the similar M20 Utility Car, although the M3A1 was retained for rear area security and convoy escort duties. A small number of M3A1s were employed in Normandy. A few M3A1s were used by the US Marine Corps in the Pacific theater, but none saw combat.
General George Patton used an M3A1 Scout Car as a command vehicle, modified with additional armor and a raised fighting compartment.
A total of 11,401 M3A1 Scout Cars were allocated for supply to US allies under lend-lease, 6,987 were supplied to the British Commonwealth, 3,310 to the Soviet Union and 104 to the Chinese Nationalist Army. Some were also supplied to Free Belgian, Free French, Czechoslovak and Polish units.
In British Commonwealth service, the White Scout Car was regarded more as an armored truck, reflected in the designation Truck, 15cwt, 4x4, Armoured Personnel, and was used in a variety of secondary roles, being issued to engineer, artillery (as an observation vehicle for field artillery observers) medical (as a protected ambulance) and signals units; within the Royal Armoured Corps’ Tank and Armoured Car Regiments it usually served in Squadron or Regimental  headquarters. It was used by British Commonwealth forces in every theatre they fought in except Burma.
In Red Army service, the M3A1 was used as an armored personnel carrier by brigade and corps reconnaissance units and motorcycle battalions and regiments, operating alongside the BA-64. The M3A1 was also used as an armored command vehicle and a gun tractor for the ZIS-3 76-mm field gun, although the towing hitch proved to be unreliable, the M3A1 remained in widespread service throughout the war.
The Chinese Nationalist Army received M3A1 Scout Cars from 1942 and used them throughout the Second Sino-Japanese War and the Chinese Civil War.
After the war, many vehicles were sold, mostly to Asian and Latin American countries while they remained in Soviet service until 1947.
A few vehicles were used by Israel in the 1948 Arab–Israeli War. At least one Israeli M3A1 was modified with top armor and a revolving turret. France employed its M3A1s in the First Indochina War  and the Algerian War.
By late 1990, the only country with the M3A1s remaining in service was the Dominican Republic.
M3 Scout Car