|all 80 HP of it
Regarding the Unimog itself, this one is powered by a 2.2L GAS engine. 80 horsepower. Yes this huge beast is powered by something that originally had only 80 hp, I wonder how much is left. A multitude of gearing (trans, transfer case, portal axles/hubs) is what allows that little bit of power to push this big of a machine up and over anything realistic. They were never (officially) sold stateside so its pretty cool to see these imported ones over here.
More pics -> http://jalopnik.com/5704715/fots-1964-mercedes-unimog-gallery//gallery/1
Source -> http://jalopnik.com/5704716/found-off-the-street-1964-mercedes-unimog
Below is a bus-style Unimog (they came in dozens of body/chassis configurations from 2-door pickup to soft-topped troop transport as seen above) that I rode in while in Germany a few years back.