Toyota launches new Prius in Detroit

Toyota released the original Prius sedan in Australia with the information that the name for the car was a Latin word meaning 'forerunner'. Presuming that calling the car by the English translation would have confused it with the HiLux-based 4Runner that had been discontinued not long before, the Latin name made sense in a way.

Now that the company has released an altogether new model to replace the hatchback released in 2004, the translation of 'Prius' has changed from 'forerunner' to 'to go before', according to Toyota. We're working on the presumption that the context is 'to go before the oil runs out'. Whatever.

The new car was unveiled this week at the North American International Auto Show in Detroit. Once, a new hybrid model from Toyota would have been unusual if not exceptional, but at this show, it's neither.

Not to show disrespect for the Prius, which has altered the purchasing decisions of a rather large sector of the car-buying public, but hybrids are increasingly common. All the (failing) Big Three manufacturers in America can sell you a hybrid vehicle of some kind -- provided you live in America.

So perhaps that's one of the major tasks facing the new Prius... to retake the initiative from other companies following the lead of the one that 'goes before'.

As the Carsales Network originally reported (more here), the new car gains a 1.8-litre engine in lieu of the 1.5-litre unit fitted previously. According to Toyota, the new engine provides more torque from lower engine speeds, allowing taller gearing and less fuel use at constant highway speeds. As a bonus, should the driver need more power and acceleration, the larger engine will deliver that too, with a second knocked off the time from standstill to 100km/h -- although it's still not blistering.

Since the water pump for the engine cooling system is electrically-driven and the starter is also a generator/alternator, the four-cylinder petrol engine is free of drive belts for ancillaries. It runs an Atkinson cycle, which is like a modified Otto cycle with a longer power stroke before the exhaust valves open. By coupling it via an open differential -- acting as a continuously variable transmission (CVT) -- to an electric motor that also generates electrical charge when spun in the reverse direction, the petrol engine (Internal Combustion engine, or 'IC' for short) supplies its torque to the front wheels, and the computer-controlled electric motor can complement it when added performance is required.

On the overrun (when the car is decelerating), the petrol engine continues to run in the same rotational direction, but forces the electric motor to run in the reverse direction, acting as a generator and replenishing the battery-based power storage. The Prius can also run -- for 2km -- on electric power alone, if the driver chooses.

This system, which Toyota names Hybrid Synergy Drive Technology, works along the same principles as in the second generation Prius, but Toyota claims 90 per cent of the drive system is new in the third-generation vehicle and the driver can choose any of the three operating modes (economy, power and electric-only).

The engine develops 73kW of power and 142Nm of torque. When added performance is required, the electric motor kicks in its 60kW and 207Nm of output. On those occasions the electric motor is operating as a generator, it recharges the Nickel-metal Hydride battery storage.

At the launch of the new model in Detroit earlier today, Toyota Motor Sales (US) Group Vice President Bob Carter (pictured) took us through the ways the new model has been revised from the old. For a start, it's slightly larger all around. There's "less than one inch" difference in length and width between the old and the new, according to Carter, and the height and wheelbase are "approximately the same".

The reason for the dimensions remaining close to those of the previous cars can be traced back to the need for aerodynamic efficiency. Toyota was starting from a high base in the second-generation car when it set about developing the third-gen model, but as we all know well, once you're locked into a drag-free shape, it's hard to deviate much from that without losing the aerodynamic virtues of the older car.

"You can spot a Prius from a hundred yards away," says Carter.

"The already sleek design has been further enhanced with a more dynamic exterior, underbody panels and sharp corner edges, as well as a larger spoiler.

"Our designers moved back the peak of the roof almost four inches [99mm], which improves rear-passenger headroom."

Carter puts the increase in spaciousness for the new car at "five cubic feet" (141 litres), which is impressive, given the aerodynamic constraints for the new design.

And that's probably the most outstanding point about the new Prius; its aerodynamic coefficient of drag -- just 0.25Cd. Toyota claims that this makes the Prius the slipperiest production car in the world and off the top of our heads, we wouldn't argue the point. That achievement, along with the changes to the engine and drive system have resulted in an improvement in fuel consumption from the 46MPG of the old car to 50MPG (4.7L/100km) for the new model. Those figures are based on American units of measurement and testing; Toyota Australia expects the new car's combined cycle consumption to be around 4.0L/100km, possibly lower.  

When the Australian-delivered car goes on sale in July of this year, it will come with a multi-function information display panel, but not the lane-change facility or 'Safety Connect' option available to American buyers.