Test pilots reported speed, acceleration and maneuverability as well as or superior to any single engine aircraft.

Items needing improving were the rearward visibility and a tall, somewhat weak, landing gear structure necessary for propeller clearance. Later versions of the Pfeil had rear view mirrors in blisters added to the canopy, improved engine cooling, and redesigned landing gear doors.

The concept for the Do-335 came from the Dornier flying boats with push-pull engines built during World War I. Advantages of the design were less drag, better control in case of loss of one engine and better maneuverability.

By 1939 Dornier had designed a bomber with the push-pull layout. Prototypes proved the effectiveness of the design, but the aircraft never went into production. That is because the German government cancelled all aircraft projects taking over one year to complete.

By the spring of 1944 Dornier submitted an updated version of his bomber. It received funding by the German government and was designated the Do-335. However, later that year the government changed the requirements of the aircraft from a bomber to that of a fighter bomber. Dornier had to modify his bomber to meet the new requirements and that delayed production.

Ten Do-335 aircraft were ready for testing in May of 1944. Upgrades to the original design incorporated the more powerful DB603E-1 engines plus additional weapons and fuel capacity. By the end of the war only a total of fourteen Do-335 aircraft had been produced.