Petrol-driven, it has cast iron engine blocks and aluminum cylinder heads, which are of a single overhead cam lean burn design with belt-driven camshafts.
[2] The engine was developed with some haste in order to replace the two-stroke "ZM" engines used in Daihatsu's earlier Kei cars, and was the first unit to take full advantage of the new 550 cc displacement limit in effect from 1 January 1976.
The AB-series is a 547 cc (0.55 L) version, originally installed in the 1976 Fellow Max 550 but was eventually used in Daihatsu's entire Kei car lineup.
Due to its larger size, it does not meet Kei car regulations; it was intended only for export markets.
Of Daihatsu products, only the Cuore (often called "Domino" in export markets) was fitted with this engine.