Manufacturing of transportation fuels incorporates a number of generations of technology, viz. (1) refining processes to arrive at the desired product quality, (2) conversion processes to balance the feedstock supply with the product demand, (3) processes to steer product composition and (4) synthetic fuels. In going from (1) to (4), the thermal efficiency of the processes tends to decrease and is affected by a number of (process) principles which are discussed here. Recent progress and future needs are discussed for all four areas of fuel manufacturing.