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Toyota's hybrid system gets a transmission overhaul for SUVs.

Toyota's goal with its second-generation hybrid system for SUVs (THS-II for SUVs) were improved fuel efficiency and power performance, compared with the Prius THS-II, to counter the conventional wisdom in the market that hybrid-vehicle performance is inferior to that of conventional vehicles. The company also wanted to introduce a hybrid system that could be installed in a front-engine front-wheel-drive vehicle of the heaviest class, and then serialize the system in the future so that it could also be integrated into any medium- or small-sized vehicle of the same configuration.

One of the key elements of the THS-II for SUVs is a new P310 hybrid transmission, development objectives of which were compact size, improved performance and fuel economy, and noise reduction. The basic construction of the transmission is similar to that of the Prius P112 unit, but the P310 has a motor speed reduction device that allows motor torque to increase without increasing motor size.