The Bf 109C variant was the last production model of the 109 fighter series designed to use a Jumo engine. The engine it mounted, the 700 horsepower Jumo 210Ga, was fuel-injected, providing it with greater high-altitude speed and maneuverability.
This new fuel-injection system also greatly decreased the chances of stalls during dives. Unlike traditional carburetor engines, the Jumo 210Ga would not lose power under negative g-force.
The new engine changed the overall shape of the aircraft. The under-nose air intake was now much larger than older Messerschmitt fighters.
The Clara's armament was upgraded from the two MG 17 machine guns of the previous model, to four. Like the Bertha, the Clara featured two machine guns in the nose, but the Clara also featured one more gun in each wing. This addition solved the biggest flaw with the previous designs; the underwhelming armament.
After their completion in early 1938, the Bf 109Cs were rushed to Spain to relieve and reinforce the Condor Legion.
In total, only 58 Messerschmitt Claras were built. 
Bf 109C-0: Pre-production model, identical to the C-1.
Bf 109C-1: The standard model with four machine guns; two in the nose and two in the wings.
Bf 109C-3: Experimental version with two MG FF 20mm cannons in the wings, instead of MG 17s. Never entered production.
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 http://www.historyofwar.org/articles/weapons_bf_109C.html
- ↑ 2.0 2.1 2.2 2.3 2.4 http://www.airpages.ru/eng/lw/bf109bcd.shtml
- ↑ 3.0 3.1 3.2 http://acepilots.com/german/bf109.html
- ↑ 4.0 4.1 Ritger, Lynn. Meserschmitt Bf 109 Prototype to 'E' Variants. Bedford, UK: SAM Publications, 2006
- ↑ http://www.historyofwar.org/articles/weapons_bf_109D.html