yaris hybrid-r 01

More tech details have emerged on the Toyota concept now known as the Yaris Hybrid-R, which will make its debut in Frankfurt. An earlier teaser post had the donor correctly pegged as a Yaris, and initial specs listed that the hybrid study would have 400 hp.

The car is based on the three-door production Yaris, and features a Toyota Motorsport-derived 1.6 litre GRE (Global Race Engine) turbocharged, direct injection mill. The engine drives the front wheels, while two 60 hp electric motors powers each rear wheel in a layout as that used in a standard Yaris Hybrid.

In combination, the hybrid powertrain offers a maximum outout of 414 hp. The two electric motors supplement the petrol engine’s performance under acceleration, and work as electric generators when the car is braking.

The system also makes use of a supercapacitor to harvest and store energy, similar to the TS030 Hybrid Le Mans car. Compared to the standard nickel metal-hydride battery used in the Yaris Hybrid, the supercapacitor has a higher power density and a fast power charge/discharge speed, meeting the demands of track driving with its ability to deliver brief, immediate bursts of power.

The level of power depends on the duration of energy delivery that’s required – in “road” mode, the supercapacitor releases energy for a maximum 10 seconds per charge, and the total power of the two electric motors is reduced to 40 hp. Switching to “track” mode makes the maximum output from the two motors available for up to five seconds per charge.

yaris hybrid-r 02

There’s also a third 60 hp motor, located between the engine and six-speed sequential transmissions. This one operates as a generator – during deceleration, to feed power to the supercapacitor, and during acceleration, to power the two rear electric motors.

The latter only happens when engine power and torque exceed the front wheels’ grip limit. Essentially, the generator works like an advanced traction control system, redirecting torque as electric energy to the rear wheels, boosting acceleration and improving handling aspects.

The rear electric motors also influence the Yaris Hybrid-R’s handling when cornering. It accomplishes this by altering the torque distribution between the left/right rear wheels, working independently as either generator or motor, in the vein of an intelligent torque vectoring differential.

Depending on the radius of the curve, the system can send more torque to the outside rear wheel, allowing higher entry speed into middle-speed bends. Conversely, it can apply more braking force to the inside wheel in fast curves, or even brake and accelerate each wheel independently in slow corners to adjust the yaw effect for a better line as well as limit steering angle and understeer aspects.