The M V1 was to be the first prototype. It was a E-2 conversion with altered cockpit and DB 603 engines. It operated from the central Luftwaffe Erprobungstelle aircraft test center at Rechlin from September 1942. During the winter the prototype performed long-range and high altitude flights. On 16 November it was forced landed for unstated reasons. Different engine-cooling systems were tried and flame retarders added. Although the addition of the dampers caused a reduction in speed of 15 to 25 kph depending on altitude. The first production prototype series M-0 aircraft (M-01) crashed in Lake M�ritz, near the location of the Rechlin test base, on 9 September 1942 while on an engine test. The M-02 was given wing reduction to 59 m2, which became the predecessor of the M-3. The M-03 refined the design with DB 603 A-1 engines but crashed after a mid-air collision with a Dornier Do 215 on 14 May 1943. Six 0-series aircraft (Wrk Nr. 1241 to 1245) were manufactured. Rechlin log books in cluded frequent references to a M-04 from December 1942 to May 1943. This aircraft was apparently used for de-icing and cabin heating tests as well as high-altitude testing with DB603s. Some M-0s were used to evaluate performance with glide bombs (Wrk Nr. 1244 and 1245). These aircraft were named M-0/U1. Each had an ETC 2000 XII, under the fuselage.