Martin XB-27

We make a small break from the Marauder in order to present you a never-built aircraft from Martin's.
The Martin XB-27 was a proposal by the Glenn L. Martin company to fill a need in the United States Army Air Corps for a high altitude bomber. It was strongly based on the Martin B-26 but it never went beyond the blueprints.
It was expected to be powered by two Pratt & Whitney R-2800-9 radial engines delivering each of them 2000hp (1500Kw) each, a fully pressurized cabin with a crew of seven and was going to be armed with three 0.30in machine guns, one in the nose, another dorsal one and a ventral one and a 0.50in machine gun placed in the tail and a payload of 4000lb (1800kg) of bombs in an internal bay. The expected maximum speed was 375mph (603.5Km/h).

Sources:
1. https://en.wikipedia.org/wiki/Martin_XB-27
2. http://www.joebaugher.com/usaf_bombers/b27.html