The 37a is recognizable because it uses the same body as the Type 35 which was introduced in August 3, 1924.

The Type 35 was phenomenally successful, winning over 1,000 races in its time. It took the Grand Prix World Championship in 1926 after winning 351 races and setting 47 records in the two prior years. At its height, Type 35s averaged 14 race wins per week. Bugatti organized the Targa Florio as a special spotlight for this car, and it claimed victory there for five consecutive years, from 1925 through 1929.

Only 290 Type 37s were built. 67 of these were supercharged Type 37As. It was fitted with a new 1.5 L (1496 cc/91 in³) straight-4 engine. This engine was an SOHC 3-valve design and produced up to 80 to 90 hp (59 to 67 kW). The same engine went on to be used in the Type 40.