J Scoltock, Boosting diesel efficiency, Professional Engineering, January/February 2021, p 47

Whereas electric propulsion appears suited to light vehicles, but not yet to commercial counterparts, Bosch and Weichal Power have teamed to raise the thermal efficiency of diesel engines from 46% to 50% through improvements in air passages, fuel injectors, combustion chamber profiles, exhaust energy distribution, emission control, lubrication technology and engine control systems. A thermal efficiency of 55% is now targeted.