The C series was a pre-production bomber powered by DB 601A engines and original shallow fuselage. It had five MG 15 machine guns installed and 3,000 kilograms (6,600 lb) bombs as its main offensive armament. Five were built and used as test beds. The V9, which had acted as a prototype for the E variant was also used for the C-0 series. The C-0 was a three crew combat aircraft powered by Jumo 211B engines and had a four-bladed 3.8 m airscrew. The RLM found no faults with the new machine in a June 1939 inspection. The only minor complaint was the limited view from the pilots' seat. Apart from the same engines and small fuselage space inherent in C-series aircraft, externally the C looked like the A-0 series. On 12 November 1940 Dornier increased the number of the crew to four to enable the five MG 15 weapons in the A, B and C-Stand positions to operate with the maximum protection. The bomb bay had also been modified to take four SC 500 or multiple SC 50 bomb loads. The Do 217 C-0 was equipped with a Lotfe 7A bomb aiming system and a Revi 12C sight for the pilot. For high-altitude flight sixteen 32-litre oxygen bottles were installed. The C-0 was capable of achieving a maximum speed of 475 kilometres per hour (256 kn) at an altitude of 5,600 metres (18,400 ft). Carrying a full operational load, its maximum speed was reduced by 20 kilometres per hour (11 kn).

The first Do 217 series aircraft, Wk Nr. 2710 flew on tests between September 1940 and March 1941. It crashed on 2 July 1942 at Rechlin. The second C-0 prototype was fitted with dive brakes on the under side of the wings but this configuration was abandoned in January 1941 and replaced by a brake parachute installed in the tail. The third prototype flew on 6 September 1940 and four further machines flew between September and November 1940. The final machine, 2716, flew on 6 November 1940. The eight machines remained at Rechlin in various test bed roles until at least July 1942. The C series project was abandoned and its variants never entered mass production.

Sources:
Gunston, Bill - The Encyclodepia of the Worlds Combat aircraft, 1976, Chartwell Books, Inc., New York
Brown, Eric, Captain - Wings of the Luftwaffe, 1979, Airlife Publishing Ltd., Shrewsbury
Gunston, Bill & Wood, Tony - Hitler's Luftwaffe, 1977, Salamander Books Ltd., London
Donald, David - The Complete Encyclopedia Of World Aircraft, 1997, Brown Packaging Books Ltd., London
Wikipedia - Dornier Do 217