Toyota Yaris Hybrid: Prius petite

May 30, 2012 § Leave a comment

Toyota has re-engineered its hybrid powertrain to supermini-size. The Yaris Hybrid is fitted with a thoroughly reworked version (73bhp, 111Nm) of the 1.5-litre Atkinson cycle engine from the Mk2 Prius, rather than the 1.8 in the latest model and the Auris Hybrid, and downsizing has been a key theme of its development. The weight gain has been controlled – the Hybrid weighs just 20-55kg more than the 1.33 manual, depending on version – and as it has no clutch, starter motor, alternator or timing belt, servicing and maintenance should be simple and affordable. The 120-cell nickel-metal hydride battery pack (cheaper than lithium-ion) fits completely under the rear seats, so luggage and passenger space are unaffected, and Toyota’s boasting that this car has the smallest hybrid transaxle it has yet produced – all the components, including motor and generator, fit inside the transmission casing. Attention to downsizing detail gets right down to the level of the coils inside the Denso-supplied motor (45kW, 169Nm), which have space-saving flat-wound instead of round wires.

The latest Yaris platform was developed from scratch to accommodate this hybrid powertrain, which is largely shared with Toyota’s domestic-market Aqua and US-bound Prius C subcompacts but specifically-tuned and calibrated in Europe for our driving conditions and tastes. Despite the economies of scale, however, Toyota thinks plug-in capability, though possible, will be too expensive to engineer into a car in this sector in the near future. Further down the line, the two-cylinder engine in the hybrid FT-Bh concept car gives a few clues as to Toyota’s thinking in the small-car sector, however.

End result is a vehicle which is lively to drive around town and capable at highway speeds, illustrated by a 0-50kmph time of five seconds, a respectable 0-62mph time of 11.8 seconds and a top speed of 103mph. And whilst the claimed combined fuel economy of 79mpg (15-inch wheels) or 85mpg (16-inch), and carbon dioxide emissions of 79 or 85g/km, may not be representative of real-life returns for the heavier-footed, the benefits of the active regenerative braking system and the all-electric mode (manually selectable for engine switch-off in city traffic) are tangible. I’m less convinced, however, by the selectable Eco mode to modulate throttle response and air conditioning, and the ‘B’ transmission mode to optimise braking energy recovery, both making quite a compromise to the driving experience; I suspect that most owners will leave this clever little car in fully automatic and self-selecting operation, where it proves to be perfectly pleasant.

Deliveries start in July and prices are from £14,995. This may sound steep for a supermini, but take into account the CVT gearbox and the high spec, as well as longer-term savings on vehicle excise duty/company car tax, fuel, the London congestion charge and soforth. IThat’s most of the benefits of the Prius in a smaller, more affordable – and still pretty damn roomy – package.

*More techy detail to follow here in the July 2012 issue of Electric & Hybrid Vehicle Technology International; more news on Toyota’s electrification strategy here at The Charging Point. Thanks to Toyota GB for the test-drive trip this week.

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