The Honda hybrid system that debuted in the 1999 Honda Insight was IMA, short for Integrated Motor Assist.
Honda designed IMA as a compact parallel-hybrid system. A gasoline engine supplied the main propulsion, while a thin electric motor mounted between the engine and transmission provided extra torque during acceleration and captured energy during braking. Its relatively simple layout helped keep the original Insight light and aerodynamic.
The first-generation Insight was introduced in Japan in November 1999 and became Honda’s first production vehicle to use IMA. The two-seat hatchback combined the system with an aluminum body, a small three-cylinder gasoline engine, and exceptionally low aerodynamic drag. Honda later adapted IMA for vehicles including the Civic Hybrid, Accord Hybrid, and CR-Z.
IMA is easy to confuse with Honda’s later e:HEV or i-MMD systems, which use more sophisticated motor-driven architectures. SH-AWD, by contrast, is an all-wheel-drive system rather than Honda’s name for the Insight’s hybrid technology.