Lexus GS 450h

Lexus Hybrid Drive represents a paradox: delivering high performance with fuel efficiency and emissions levels beyond the capabilities of comparable, conventionally powered vehicles.

The GS 450h has a completely new, front engine, rear-wheel drive, series/parallel hybrid powertrain. It uses a 3.5-litre V6 petrol engine with a new D-4S (Direct-injection 4-stroke Superior-version) twin injector system with Dual VVT-i (Variable Valve Timing – intelligent), developing 292bhp (296 DIN hp) and 368 Nm of torque, mated to a compact, high-output, permanent magnet electric motor that generates 197bhp (200 DIN hp) and 275Nm of torque right from standstill.

With a combined power output of 341bhp (345 DIN hp), the GS 450h was the world’s first production hybrid car to achieve the 100 DIN hp per litre benchmark.

In addition to the petrol engine and electric motor, the Lexus Hybrid Drive system also features a generator, a high-performance 288V nickel-metal hydride battery, a Power Split Device and a new, compact Power Control Unit that is no larger than an auxiliary 12V battery (and 63 per cent smaller than the one used in the RX 400h).

The hybrid transmission incorporates a two-stage motor speed reduction gear. The mechanism is similar to a very compact automatic gearbox and generates maximum low-gear torque for significantly better acceleration, and extended high-gear performance for quiet, high-speed cruising with improved fuel efficiency.

The electric motor, generator, Power Split Device and two-stage motor reduction gear are all housed in a single, lightweight, compact longitudinal transmission casing that is just one centimetre longer than the six-speed manual transmission in the Lexus IS.

Another world-first is the GS 450h’s Electronically-controlled Continuously Variable Transmission – E-CVT – with sequential shift mode. Each of the six sequential ‘steps’ gives sharper engine braking force, in the manner of a conventional automatic gearbox in sequential mode. This improves vehicle control and the sports driving experience.

The GS 450h can accelerate from nought to 62mph in 5.9 seconds and from 50 to 75mph in 4.7 seconds, maintaining linear acceleration all the way on to a top speed of 155mph, with none of the typical ‘jumps’ between gears experienced in a conventional drivetrain.

At the same time, the GS 450h is substantially more frugal than comparable V8 models, returning 35.8mpg in combined cycle driving, fuel consumption that is on a par with D-segment petrol cars. Carbon dioxide emissions are 185g/km, which matches the performance of four-cylinder economy diesels in the premium segment, and combined emissions of nitrogen oxides (NOx) and hydrocarbons (HC) are extremely low at 0.01g/km.