How did diesel locomotives improve operating efficiency compared with steam locomotives?

Diesel locomotives significantly improved operating efficiency over steam locomotives by offering superior reliability, fuel economy, and performance capabilities. The primary advantages included:1

• Reduced Maintenance: Unlike steam locomotives, which required extensive servicing after only a few hours of operation, diesel units could run for long periods without lost time for maintenance. This allowed for much longer continuous hauls.1
• Higher Thermal Efficiency: Diesel traction units utilized fuel energy more effectively, boasting a thermal efficiency approximately four times greater than that of steam locomotives.1
• Improved Performance: Diesel locomotives provided more rapid acceleration and could maintain higher sustained speeds while causing less damage to the track.1
• Operational Flexibility: Diesel units offered cleaner operation and standardized repair parts. Additionally, multiple diesel units could be combined and managed by a single operator using multiple-unit control, increasing operational versatility.1

Later advancements in the 20th century, such as improved power-to-weight ratios and the integration of electronics for "creep control," further enhanced load-hauling capabilities and adhesion, allowing for more efficient freight transport with fewer locomotives required.2