The fourth-generation Toyoace that came out in March 1979 addressed the social concerns of the time by complying with 1979 emission and noise standards and featuring enhanced safety measures, while expanding model variations to respond to the increasingly diverse customer needs. It also adopted the full cab-over-engine design to enlarge the cabin and improve the ease of boarding and exiting. The loading/unloading of cargo also became easier, while the drivability improved as well. The specifications and equipment including the seats were also upgraded, making the Toyoace as comfortable to ride as a passenger car. The lengths of the body and the deck remained virtually the same as the predecessor's, although the wheelbase was shortened by 345 mm to reduce the minimum turning radius by 0.7 meter.

In addition to the 2.5-liter diesel engine (2J) inherited from the previous model, a 2.2-liter SOHC unit (Type L) was made available, and the number of diesel engine-equipped models increased from seven to 25. Furthermore, the Toyoace offered 20 models equipped with either a 1.6-liter (2R) or a 2-liter (5R) gasoline engine, satisfying a wide variety of needs.