Lexus hybrid torquing loud and clear

The world's first rear-drive hybrid Lexus GS450h.

The engine management system in Lexus' first hybrid sedan knows immediately when its driver wants to use the instant torque of the electric motor to blast off from a standing start.

"It will say to itself, 'okay, we've got a nutter at the wheel'," says Doug Soden, the Australian product planning manager for the GS450h four-door.

"So it adjusts the torque from the electric motor to launch the car off the line."

There were plenty of nutters at the launch around the Mt Panorama race circuit of the luxury carmaker's latest model, the world's first rear-drive production hybrid.

The GS450h couples a 650-volt electric motor/generator with a 3.5-litre V6 petrol engine to produce a combined 254kW (340bhp) of power.

On its own the electric motor produces 147kW (200bhp) and 275Nm from zero revs. The V6 delivers 218kW (295bhp) at 6400rpm and 368Nm at 4800rpm.

But like all hybrids the power is mixed and matched so there is not full power. .

Lexus says the unit delivers 22 per cent more power and 31 per cent better fuel economy than the flagship LS430 V8.

The power goes to the road through an Electronic Continuously Variable Transmission (ECVT). Lexus used the start of the Mt Panorama mountain straight to show off the instant power of the electric motor and the benefits of the ECVT transmission.

With no clutch, no torque converter and no belts and pulleys in the ECVT unit there is no slippage and no wasted energy.

Under full throttle, maximum system performance is delivered through both the petrol engine and the electric motor.

The GS450h blasted off the line from a silent start before the petrol engine kicked in to seamlessly reach 100km/h in under six seconds and on to around 170km/h. Track marshals flagged drivers down to a legal 60km/h around the rest of the circuit, which was steeper and with more twisting turns across the top of the mountain than it seems on TV.

Former Australian rally champion Neal Bates ("I miss Possum, mate. Miss his desire for the sport") has been testing the GS450h and its variable suspension on the track. The system allows the driver to select the standard mode or a firmer, more focused sport mode.

"I took it around Oran Park against the 430 V8 and it beat it hands down," Bates said. "Off the line it was a car length in front of the V8 after 50 feet.

"It took some getting used to. It's so quiet. I'm used to driving cars that make a lot of noise."

The increase in performance is achieved through two electric motors, which also function as generators.

One acts as the car's starter motor, and as a generator for recharging the battery. The other provides additional drive for the car in tandem with the V6 petrol engine and recaptures energy for storage in the hybrid battery.

The system allows the petrol engine to automatically switch to electric power to save fuel and cut exhaust emissions when the vehicle is stationary, travelling at low speeds or decelerating from low to medium speeds.

Lexus says the combination provides the power of a 4.5-litre V8 and the fuel economy of a 2.5-litre car.

The GS450h costs $130,000 and is virtually the same in appearance and specification as the V8-powered GS430 launched in New Zealand a year ago. The only obvious difference are new 18-inch aluminium alloy wheels, a GS450h badge on the rear boot, and hybrid badges below the rear passenger doors.

The passenger cabin is similar to GS models. However, there is a new combination meter on the dashboard, replacing the conventional tachometer with a kilowatt meter which shows how much power is being developed. It also indicates the level of energy being recycled through the system to be stored in the battery.

A touch-screen displays such information as the operating state of the hybrid system, vehicle performance, fuel consumption and cruising range, as well as conventional GS functions including audio, climate control, and bluetooth telephone connection data.

The audio system features an in-dash six-disc CD changer, with 10 speakers, or, as an option, a Mark Levinson premium audio DVD system with 14 speakers. The system also plays DVDs.

The GS450h comes with everything that opens and shuts, including 10 airbags and a radar sensor that adjusts the car's speed to maintain a set distance from the car in front.

It is the first in a line of Lexus hybrids that will include the RX four-wheel-drive and LS flagship.

Lexus and its parent Toyota expect to deliver more than one million hybrids over the next two years, despite criticism from rivals that hybrids aren't cost-effective. It says car companies that ignore hybrid technology do so at their peril.

"Initially some people considered hybrid vehicles as a temporary means to facilitate the transition from internal combustion engines to fuel-cell hydrogen vehicles," it said in a paper.

"However, it is now realised that hybrid technology is indispensable for improving the efficiency of vehicles driven not only by gasoline engines, but also by diesel and alternative fuel engines as in fuel-cell vehicles."