Jody;
Hi!
It's actually the "kleines kettenkraftrad", or "kettenkrad", for short. The Sd.Kfz. 2.
Kettenkrad used the small Opel in-line 4-cyl engine used in the Opel "Olympia" car (Opel Olympia mod. 38). This little water-cooled engine was rated somewhere between about 28 bhp and 36 bhp.
PS: the Opel Blitz truck used a much-larger engine - first production (up to 1937) used a 68 bhp Buick in-line 6-cyl, 1938-on used the yet larger (and more modern design) 75 bhp Opel straight-six as also used in the Opel "Admiral" saloon-car. This latter engine was essentially the GM straight-six as seen under Chevy hoods of the period. Who ever said that the Germans had to do all of their wartime vehicle design and production on their own?
Cheers!
Bob