Perhaps the most significant fuel saver for refrigerated hauling is electric standby operation. By using standby power when the trailer is parked, product temps are maintained without burning diesel fuel at all.
Guchen Thermo's refrigeration units have always included an electric standby feature, which provides 100% of the rated refrigeration capacity when the refrigeration unit is plugged into AC power. This can save 40–70%, due to the lower cost of electricity vs. diesel.
Since a large part of a refrigeration unit’s runtime can be for loading and unloading, the fuel savings over the course of a day can be significant when you can plug in at the dock.