Alternative Fuel Engine segmentation by type distinguishes five principal architectures: internal combustion engine (ICE), hybrid engine, fuel‑cell engine, rotary engine, and turbine engine. The ICE category remains the largest contributor, accounting for roughly 55 % of total market volume, because legacy vehicle platforms can be retrofitted with biodiesel, ethanol, or natural‑gas blends with minimal redesign. Hybrid engines, which combine a conventional ICE with an electric motor, capture about 20 % of the market, driven by regulatory mandates for reduced emissions in passenger‑car segments. Fuel‑cell engines, employing hydrogen or methanol as feedstock, represent an emerging 12 % share, reflecting early‑stage adoption in logistics and public‑transport fleets. Rotary engines, prized for compactness and high power‑to‑weight ratios, hold a niche 8 % position, primarily in marine auxiliary power units. Turbine engines, optimized for liquid‑fuel alternatives such as synthetic kerosene, contribute the remaining 5 %, largely within aviation and offshore power generation contexts. Collectively, these sub‑types define the structural backbone of the Alternative Fuel Engine market and determine investment priorities across the value chain.