A report dating back to February 17th, 1945. Grafenwöhr, Grossdeutschland.

At the request of the Oberkommando der Wehrmacht, the newly introduced Sd. Kfz. 191 (PzKpfw. E-50 Ausf. B) has been compared to the Sd. Kfz. 182 (PzKpfw VI Tiger Ausf. B). The tests have been conducted at the training ground in Grafenwöhr, Bavaria.

Size
The E-50 Ausf. B is a lot smaller compared to the Königstiger.
Königstiger dimensions: 10.29 x 3.76 x 3.09 (L x W x H)
E-50 Ausf. B dimensions: 9.57 x 3.42 x 2.61

Armor
While the Königstiger has very thick armor, the layout is rather outdated. The front is 150 mm thick angled at 50* horizontally. The E-50B features a 135 mm plate angled at 30* horizontally. Practically, the E-50B has much better protection, increasing the chances for shells to bounce.
The turret front is 180 mm on the Königstiger at 85* horizontally and, on the E-50B, 175 mm at 70* horizontally. They both feature similar protection.
The sides are 80mm on both tanks at 80* horizontally.
Rear armor is different. The Königstiger has an 80 mm plate angled at 75* horizontally, while the E-50B has two plates: a 35 mm upper plate angled at 80* horizontally and a 25 mm lower plate angled at 75* inwards.
Turret sides and rear on the Königstiger are similar: 80 mm both. The E-50B turret sides are made out of two pieces each: a front (110 mm) and a rear (65 mm) one, both angled. The rear plate is only 30 mm angled at 80* horizontally.

Mobility
The Königstiger suspension is overloaded: the maximum load weight is 67 t, but the tank weighs nearly 68.7 t.
The E-50B weighs little over 49 t, but the suspension allows for up to 52 t.
The Königstiger features a Maybach HL234 850 hp engines, while the E-50B has a newly developed HL234 P47 1000 hp engine.
The Königstiger can only reach 40 km/h in ideal road conditions. The E-50B, being much lighter, can go up to 54 km/h.
The Königstiger has a low power/weight ratio of 12.37 HP/t, while the E-50B has a power/weight ratio of 20.3 HP/t.
The tracks on both vehicles are identical: 800 mm wide.

Main armament
The Königstiger uses an 88 mm KwK 43 L/71 high-velocity gun that can shoot APCBC, APCR, HE and HEAT rounds at 1000 m/s || 1130 m/s || 590 m/s || 610 m/s.

The E-50B uses a 105 mm KwK 45 L/52L high-velocity gun that shoots APBC-HE, newly developed APDS ammo (inspired by the one found on the Sherman Firefly 17 pdr guns), HEAT and HE rounds at 1150 m/s || 1490 m/s || 570 m/s || 600 m/s.

The results have been carried on a 300 mm thick rolled homogeneous plate.
They have been conveniently placed in a table as follows:

Both tanks can depress their guns at 8* and elevate them at 15*.

Secondary armament
The Königstiger has two MG-42 machine guns (one mounted on the hull, the other on the commander's hatch).

The E-50B has only got one MG45 machine gun (mounted on the commander's hatch).

Optics
Both tanks use the same commander's hatch design, featuring 8 periscopes. In addition, both have a ZG 1229/1 that can be used by the commander. In addition, the E-50B has infrared sights for both the gunner and the driver.

Inner layout
The Königstiger has 5 crew members. The driver and the radio operator were sitting in the hull front, while the commander, gunner and loader were sitting inside the turret. It stores most of its ammo inside the hull (66 rounds) and 20 rounds inside the turret.

The E-50B has 4 crew members. The driver sits alone in the hull front, while the commander, gunner and loader are sitting inside the turret. The commander can switch places and sit next to the driver if needed. It stores most of its ammo at the back of the turret (35 shells), while only 10 shells (5 on each side) are inside the hull. The ammo is rather limited on it.

Communication
Both the Königstiger and the E-50B are using a FuG 7 radio, providing 50 km of range under good weather conditions.

Additional comparison pictures:

Verdict: The E-50 Ausf. B is, overall, a much better-suited tank for the battlefield compared to the Königstiger. The relatively low production and maintenance costs (costing only 122.550 RM to build), high reliability and good armament, it should be immediately put into mass production.