Shares in Britain’s engineering and technology firm Torotrak Plc lost nearly 60% of their value after it emerged that GM will not exercise its option to purchase the company’s innovative fuel-cutting Infinitely Variable Transmission (IVT) technology.

GM’s decision follows Toyota‘s withdrawal at the end of 2000. However, the company has plenty of other existing licensees including Ford.

Analyst and transmissions specialist Mark Wilkinson said: “GM’s decision is not wholly unexpected in the current cost-cutting climate. However, the company has plenty of other licensees and there is still great interest in its technology. Ford, for example, is still testing IVT.”

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IVT (also known as a toroidal transmission) has been in development for many years. It is based on a simple arrangement of input/output discs and variable angle rollers that run between them-without the need for the belt used in Continuously Variable Transmission (CVT).

Torotrak developed and patented the system and continues to develop it for a number of car and gearbox makers around the world.

A Japanese transmissions maker (JATCO) already has a form of IVT in series production for the domestic market and Nissan has an IVT-type unit in use in some of its domestic market executive cars.