One of the planes Erich Alfred "Bubi" Hartmann.
The Bf 109 G-series was developed from the F-series airframe although there were several differences. This series used the 1,475 PS Daimler-Benz DB 605. Modifications included reinforced wing structure, an internal bullet-proof windscreen, the use of heavier, welded framing for the cockpit transparencies, and additional light-alloy armour for the fuel tank and armouring of the radiators. It was originally intended that the wheel wells would incorporate small doors to cover the outer portion of the wheels when retracted. To incorporate these the outer wheel bays were squared off. Two small inlet scoops for additional cooling of the spark plugs were added on both sides of the forward engine cowlings. A less obvious difference was the omission of the boundary layer bypass outlets, which had been a feature of the F series, on the upper radiator flaps.
The G-series was designed to adapt to different operational tasks with greater versatility, using field kits known as Rüstsätze. Special high-altitude interceptors with GM 1 high-altitude boost and pressurized cockpits were also produced.
The "new" Daimler-Benz DB 605A series was a development of the DB 601E engine utilised by the preceding Bf 109F-4. This was achieved through increasing the displacement and the compression ratio, as well as other detail improvements. The DB605 suffered from reliability problems during the first year of operation, forcing Luftwaffe units to limit maximum power output to 1,310 PS (975 kW) at 2,600 rpm and 1.3ata manifold pressure, until October 1943, when the full 1475 PS rating at 2800 rpm, 1.42ata manifold pressure was cleared for service use.