A well-engineered petrol-electric hybrid system softens the environmental impact of a sizeable SUV like the RX450h, reducing its CO2 exhaust emissions and increasing its fuel efficiency.
At the same time, as a “free” bonus, it boosts the RX450h’s point-to-point performance.
Hybrid technology is ideal for the sports utility vehicle, because an SUV tends to be heavy, thirsty and about as ecologically friendly as smoking a cigarette in a greenhouse (or a cigar if it’s a Hummer).
Here, then, is the new RX450h, which replaces the groundbreaking RX400h nearly four years after the latter’s successful debut.
The main objective of the new model is further-enhanced fuel economy, followed by improved driveability in all conditions.
Only those with an engineering degree and a paid-up lifetime subscription to Popular Mechanics can fully understand the measures employed by Lexus engineers to achieve their aims.
The rest of us just need to know that the technical highlights of the RX450h include the adoption of the Atkinson combustion cycle (which is more fuel-efficient than the usual Otto cycle) for its petrol-engine element.
There’s also the addition of a cooled exhaust gas recirculation system (again, in the quest for greater efficiency), a reduction in transaxle frictional losses (for you-know-what) and a more capable inverter system (that’s efficiency for you).
New RX interior is logical, comfortable and better built.
On the road, the RX450h is a smoother ride than the RX400h despite the new model’s larger tyres, thanks to the significant improvements in the suspension and interior insulation.
The handling feels more tractable than before and is less prone to body rolls, while the steering seems a little closer to the asphalt action.
The braking is much better now, being more progressive not only in stop-start traffic but also at highway speeds.
The squashy brake pedal feel, a characteristic of the regenerative brakes on the RX400h, has been eliminated with this new RX450h, which employs the absolute latest in regenerative braking technology.
What is the difference between a hybrid, plug-in hybrid and electric car?
Last but not least, the 295bhp powertrain’s transitions between pure battery power and full-throttle, engine-plus-electricity propulsion are now even more gentle.
And the regular engine restarts of the fuel-saving, stop-start function are a lot less noticeable now in the new hybrid RX450h.
The really fun part about driving this car is its initial acceleration.
A bigger and more powerful petrol V6, coupled with an excellent CVT, more effective motor generators and a lighter, more efficient Ni-MH battery pack, mean that it’s a bit of a green monster on take-off, more so than the RX400h, which is already no slouch from standstill.
Neat hybrid system indicator is the “tachometer”.
Yet the RX450h, thanks to its “juice-squeezing” features big and small, is said to be over 10 percent more economical than the RX400h in daily driving.
This equates to a potential mileage of nearly 14km per litre, which is very good going for an SUV of the RX450h’s size, weight and equipment level.
The on-board amenities include bags of room for passengers and cargo, hectares of leather, precise computerised climate control and electric everything.
The coolest item is the hybrid system indicator, which takes the place of the tachometer.
But it still looks like one, albeit with “Charge” as low “revs” at the 9 o’clock position and “Power” as high “revs” at 12 o’clock.
The second-coolest cabin gadget is Remote Touch, an unusual mix of mouse and joystick complete with haptic feedback, which consolidates and controls the car’s navigation, communication, set-up, air con and audio systems.
Remote Touch, however, isn’t destined for the Singapore market RX450h, due here in the third quarter.
When it arrives, the second-generation RX hybrid will, once again, make the SUV segment’s ecological impact a little softer, without compromising on comfort and suburban driveability, which it excels in.
RX450h boasts a state-of-the-art petrol-electric drivetrain.
2009 Lexus RX450h 3.5 (A)
ENGINE 3456cc, 24-valves, V6, hybrid
MAX POWER 295bhp at 6200rpm (+173kW from electric motors)
MAX TORQUE 334Nm at 4700rpm
GEARBOX CVT
0-100KM/H 7.4 seconds
TOP SPEED 200km/h
CONSUMPTION 13.8km/L
PRICE INCL. COE To be announced
