Messerschmitt Bf.110G , German users, part one

The Messerschmitt Bf.110G and the Bf.109G have a lot in common as both of them were improvements from previous versions when the aircraft expected to replace them failed to live-up to their expectations.
The aircraft that was going to replace the Bf.110 was the Messerschmitt Me.210. When Messerschmitt suggested a new version of the Bf.110 in the summer of 1941, the work on the Me.210 was going well and therefore the project of the improved Bf.110 was discarded. However, by early 1942 the Me.210 showed some serious flaws and in April 1942 the project was paralyzed. Just in case, Messerschmitt had been working on an improved version of the Bf.110 as an alternate for the Me.210 since January 1942.
The main change from the previous Bf.110F was the replacement of the engine, as the G version was powered by a Daimler-Benz DB 605B liquid-cooled inverted V-12 which delivered 1455hp of power each. As the engine was phisically similar to the previous one, alterations on the airframe were minimal. It was strengthened to fit the heavier engines, allowing that way to carry a heavier payload (It was thanks to that increase in the payload that the Bf.110G enjoyed a longer lifespan) and, as the Luftwaffe required new demands, the Bf.110G was able to carry the extra equipment required. More powerful guns, rockets, extra fuel and an increasingly complex sets of radar arrays would place more weight on the aircraft.
By May 1942 the pre-production Bf.110G-0 appeared and showed very good characteristics when encumbered, but performance decreased dramatically when it was fully loaded. That's why it's career as day fighter was very brief, but it was very successful as a night fighter, role where it excelled until the end of the war. However, by mid-1944 the Me.410 was already replacing the Bf.110G in both day and night roles.
The last Bf.110G was manufactured in February 1945, as it wasn't included in the Emergency Fighter Program of November 1944, which was an attempt of streamlining the German aircraft industry, so when the last aircraft already under construction were finished, production ended.

Sources:
1. http://www.historyofwar.org/articles/weapons_bf_110G.html
2. https://en.wikipedia.org/wiki/Messerschmitt_Bf_110
3. Salamander Books - The Complete Book of Fighters