Power and torque figures cited anywhere on this site should be read alongside the standard used to produce them. SAE J1349, ISO 1585, DIN 70020, and JIS D 1001 each specify different reference atmospheric conditions and different requirements for fitted accessories, so the same engine can carry several legitimate ratings. Chassis-dynamometer figures additionally reflect drivetrain losses and vary with the dynamometer type, the correction formula applied, and even tire pressure.
Historical dates and efficiency values referenced here are matters of public engineering record: the Otto four-stroke of 1876, Diesel's engine of 1893, the first turbocharged production cars of 1962, and the roughly 40 percent thermal efficiency reached by series-production hybrid engines in the late 2010s. Readers comparing specific vehicles or engines should consult primary test reports and manufacturer documentation rather than any secondary summary, including this one.