Toyota Aqua / Prius C

Debut: 2012
Maker: Toyota
Predecessor: No

 Published on 24 Mar 2012 All rights reserved. 

Prius is a miracle. With nearly half a million units sold a year it is by far the biggest selling hybrid car in the world. Probably the most profitable model in Toyota's lineup, too. Apart from Prius, Toyota developed many other hybrids, including Sai (Lexus HS250h), Lexus CT200h, Camry Hybrid, Crown Hybrid, Highlander Hybrid, Lexus GS450h, LS600h, RX450h, Auris HSD… too many to remember. However, none quite matches half the success of Prius. To get an annual sales volume of 250,000 units or more you need not another niche but a bread-and-butter hybrid. As Prius had already occupied the heartland, the next logical step will be the smaller compact car segment. Aqua is the one to take on this mission.

The Aqua is not the first of its kind – that should be Honda Insight. Introduced 3 years ago, the Insight attempted to lower the entry point of hybrid ownership by offering a smaller and cheaper package. Unfortunately, its fundamentally flawed IMA hybrid system failed to deliver the kind of fuel efficiency that people expect. As a result, its sales never quite took off.

The Aqua is not going to face the same criticisms, because it employs Toyota's Hybrid Synergy Drive (HSD). With two motors, one dedicated to propulsion and another optimized for generation, its efficiency should be much higher than the single-motor system of Honda. Moreover, the propulsion motor in Toyota is much more powerful than Honda's thin-disc motor (61 vs 13.6 hp), thus its electric power is available across a wider speed and load range. This mean the Aqua can run in EV mode more of the time and save fuel, especially in urban area. According to US EPA rating, the Aqua returns 53 mpg in city and 46 mpg on highway, overshadowing its rival's 41 and 44 mpg respectively.

To take advantage of the established image of Prius, the Aqua is named as Prius C – where C stands for City – in North America. We may need more time to see how successful it will be over there, but sales figures in Japan are already encouraging. In February, the second full month since it went on sale in Japan, it sold some 22,000 units, trailing only Prius and Honda Fit (Jazz) in the domestic sales chart. If the trend continues, by the end of this year more than 250,000 Aquas will be sold at its home market. In addition to the demand from American buyers, the Iwate plant in Japan is almost certain to reach its maximum volume of 360,000 units/year on 3 shifts.

The Aqua is built on the Yaris / Vitz platform. We classify it as B-segment, a class smaller than the C-segment Insight because it is some 400 mm shorter. However, its wheelbase and width are actually identical to Honda's, while its roof stands 20 mm taller. Therefore its cabin is roomy. EPA measurement shows its front occupants get much the same space as the Honda, while rear passengers enjoy 50 mm more legroom and 15 mm more headroom. Trunk space also eclipses the Insight's by 17.1 vs 15.9 cubic feet.

The hybrid system is similar to Prius, just being smaller in every way to take advantage of the car's 215 kg lighter kerb weight
at 1165 kg the car is featherweight by the standard of hybrid vehicles. The Atkinson-cycle four-cylinder engine has shrunk to 1.5 liters, producing only 74 horsepower. The electric motor is smaller too, producing 61 hp instead of 80 hp. The NiMH battery pack, sitting under the rear seats, is made of 120 cells instead of 168 cells, and have a capacity of 0.87 kWh instead of 1.3 kWh. These measures cut significant costs.

Equally cost-cutting is the interior, which features a hard plastic dashboard and simpler instruments. The 3.5-inch LCD is no larger than your iPhone's. To enable a reasonable price it has to sacrifice the expensive build quality and features that you normally expect on conventional cars.

On the road, the Aqua drives pretty much like a hybridized Yaris – that's what we can expect from the forthcoming Yaris HSD. Its body control is surprisingly good as the suspension setting is quite firm. On the flipside, ride comfort suffers on poor surfaces. Steering feel is as numb as its platform donor. Highway refinement might be helped by the teardrop shape (Cd is only 0.28), but the chassis is clearly tuned for urban drive thus high-speed stability is lacking. You won't buy the Aqua for driving fun.

The hybrid powertrain works just as expected. It offers decent performance with the help of electric motor, but it hates to be hurried. The rubberband effect of CVT leads to a delay between throttle application and actual acceleration, hence a sense of sluggish throttle response. This lack of go is made even stranger as the engine is screaming noisily at the same time. The regenerative braking is well sorted in this car, with a firm pedal. The throttle pedal is not as good, as its short range of travel makes it difficult to modulate.

All these mean the Aqua or Prius C is not going to be our choice. However, as a green city car it is still worth considering. More so than Honda Insight it combines the practicality and affordability of conventional family hatches with real gain in fuel economy. The lower running costs and tax breaks should make it appealing to many people demanding a private urban transport.

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Aqua / Prius C
Front-engined, FWD
Steel monocoque
Mainly steel
3995 / 1695 / 1445 mm
2550 mm
Inline-4, Atkinson cycle,
electric motor
1496 cc
DOHC 16 valves
74 hp (engine)
61 hp (motor)
100 hp (combined)
82 lbft (engine)
125 lbft (motor)
F: strut
R: torsion-beam
1165 kg
105 mph (c)

Performance tested by: *C&D

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Aqua / Prius C

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