Toyota introduces the B-segment Yaris Hybrid at Geneva; anticipating 20% of Yaris model range sales in first year
|Yaris Hybrid powertrain. Click to enlarge.|
The new Yaris Hybrid—the first full hybrid vehicle to go on sale in the European B-segment—made its world debut at the 2012 Geneva Motor Show. The new Yaris Hybrid, which is equipped with a version of the downsized hybrid powertrain featured in the Prius c/Aqua (earlier post), is a major step in the company’s full hybrid European roll-out strategy.
The Yaris is Toyota’s best-selling core model in Europe, with the largest Unit in Operation fleet on European roads. Following the launch of the Auris Hybrid, the Yaris Hybrid is Toyota Europe’s second core model to feature Hybrid Synergy Drive (HSD), and brings the powertrain to the biggest volume segment in Europe.
|Yaris Hybrid. Click to enlarge.|
Every key HSD component has been reduced in size, and both the fuel tank and battery are installed under the rear seat. As a result, the Yaris Hybrid maintains identical occupant space and the same 286 liter luggage capacity as that of the standard model. Fuel consumption is 3.5 L/100km NEDC (67 mpg US), equivalent to 79 g/km CO2.
The downsized full hybrid system combines the new 1NZ-FXE 1.5-liter gasoline engine with a lighter, more compact electric motor, transaxle, inverter and battery pack. Total system weight is 42 kg less than that of the Auris Hybrid, making the new powertrain 20% lighter.
The 1.5-liter Atkinson Cycle gasoline engine is 16.5 kg lighter and 10% shorter than the 1.8 liter unit of existing Toyota HSD powertrains. When used in combination with a cooled Exhaust Gas Recirculation (EGR) system, an Atkinson cycle engine offers significant gains in fuel efficiency and the reduction of emissions.
In the Atkinson cycle, compression and expansion are asymmetrical, and the valves close late, delaying compression. This creates a high expansion ratio for less compression, converting combustion energy to engine power more effectively. Though more fuel efficient, an Atkinson cycle engine is marginally less powerful than the more common, Otto cycle unit. However, it is supported by an electric motor in Toyota’s Hybrid Synergy Drive, boosting total system power under acceleration.
The use of a smaller E-CVT electric continuously variable transmission and a more compact electric motor effects a 6% reduction in the length of the Yaris Hybrid’s transaxle, and an 11 kg weight saving over that of the Auris Hybrid.
The electric motor has been made smaller through the optimisation of the magnet material, and the winding of the coils with flat, rather than round, wire. And, due to a reduction in system current and voltage, the system’s Power Control Unit (PCU) has also been made smaller and lighter through the development of a more compact inverter and switching unit.
The new, downsized full hybrid powertrain also features a smaller, NiMH battery with a more efficient management system. The number of cells has been reduced from the 168 of the current Auris Hybrid to only 120, effecting a decrease in volume of 20% and a weight saving of 11 kg. This has made it possible to install the new battery entirely under the rear passenger seats, with no intrusion into the cargo loadspace.
Combining the power of a 55kW gasoline engine and the electric motor, the Yaris Hybrid’s highly efficient, 74 kW/100 DIN hp powertrain offers a balance of performance and fuel consumption/CO2 emissions for the B-segment, whilst allowing customers frequent driving in modes that emit zero NOx, PM or CO2 emissions. Real world tests in an urban environment with Toyota’s Hybrid Synergy Drive powertrain found that up to 60% of commuting journey is undertaken with the gasoline engine off, resulting in zero emissions driving.
|Summary data derived from Toyota’s own evaluations to illustrate percent of time and distance the new Yaris Hybrid operates without its gasoline engine. Click to enlarge.|
Combining a low center of gravity with the optimum weight distribution provided by the battery pack’s central layout, the Yaris Hybrid offers customers responsive performance and well-balanced driveability.
A thorough review of Noise, Vibration and Harshness (NVH) measures has also increased the quietness of the HSD powertrain. Most notably, an excessive increase in engine rpm has been suppressed under acceleration, offering a more linear relationship between vehicle and engine speeds.
Toyota emphasized that the new Yaris Hybrid is not a niche model. It is designed to appeal to a broad range of customers from different segments, such as C-segment downsizers wishing to combine roominess with fuel efficiency, traditional B-segment buyers looking to combine style with low ownership costs, eco-minded customers seeking the latest, class-leading green technology, and even B-premium intenders in search of an alternative proposition.
With the 2,510 mm wheelbase length unchanged, the new Yaris Hybrid is 20 mm longer than the standard Yaris, at 3,905 mm overall. The front overhang has been increased to accommodate the new, downsized, full hybrid powertrain, yet the vehicle’s class-leading turning circle of only 4.7 meters has been maintained.
The new Yaris Hybrid benefits from improvements to air flow both over the restyled front of the body and, through the adoption of underbody covers and wheel spats, beneath it. As a result, Toyota’s new full hybrid offers a drag coefficient of Cd 0.286.
The new Yaris Hybrid will be produced at the Valenciennes plant of Toyota Motor Manufacturing France. Representing 20% of total Yaris model range volume sales on a full year basis, it will go on sale throughout Europe from May 2012.