Lexus RX450h v Porsche Cayenne S Hybrid 2011 Comparison

Porsche Cayenne S Hybrid
Price: $159,900.
Economy: 8.2L/100km.
Emissions: 193g/km.
Performance (0-100km/h): 6.5sec.
Powertrain: 3.0-litre supercharged V6 petrol engine (245kW, 440Nm) and
electric motor (34kW, 300Nm) produce a combined output of 279kW, 580Nm.
Eight-speed torque converter automatic transmission.
Weight: 2240kg.
Towing capacity: 750kg unbraked, 3500kg braked.
Warranty: Three years/unlimited km (no special allowance for hybrid drivetrain).

More photos of the Lexus RX450h v Porsche Cayenne S Hybrid

Hybrid Highriders
Toyota may have sold more than three million Prius hybrids hatches but petrol-electric technology has been slow to gain acceptance in the diesel-dominated SUV market.

The Japanese maker’s luxury division Lexus was the first with a hybrid SUV when it introduced the technology in the RX ‘soft-roader’ in 2003.

Lexus had the luxury hybrid SUV market to itself initially. But that changed about this time last year, when Porsche introduced a hybrid version of the second-generation Cayenne.

Both vehicles have petrol and electric power – but, as we discovered, they are fundamentally different. Here’s how Porsche’s first-ever hybrid SUV compares with the world’s first.

The hybrid RXs carry a price premium of between $9000 and $11,000 compared with their respective RX350 models, ranging from $89,788 to $108,788 plus on-road costs.

Based on the average distance travelled by motor vehicles in Australia and the current cost of fuel, it would take more than 10 years to recoup the price premium in petrol savings (when comparing the hybrid to the regular RX). But as with most emerging technology, the hybrid Lexus is more about clearing consciences rather than pinching pennies.

The world’s best-selling hybrid softroader has two electric motors. The front wheels are driven by a 3.5-litre V6, the front electric motor, or a combination of both. But the rear wheels have an electric motor of their own, which is used during take-off and acceleration when the car senses the need for all-wheel-drive grip.

The hybrid system on the new RX450h has three separate motor/generators. One generator is used to charge the battery pack and doubles as the engine starter motor. The electric motor that drives the front wheels has 123kW and 335Nm, and the electric motor that drives the rear wheels has a maximum output of 50kW and 139Nm.

The 3.5-litre V6 has 183kW and 317Nm but calculating total power and torque is not that easy… Lexus says it is not accurate to add the power and torque of the petrol and electric motors as they arrive at their peak outputs at different points. Thus the claimed peak power with all motors combined is 220kW – and the estimated peak torque with all motors combined is about 500Nm (Lexus does not make an official claim for torque).

Given that the RX has twice the number of electric motors as a Prius it also has twice the recharging power. The onboard battery pack gets topped up on the run, when the brakes are applied or when the car is coasting downhill.

The RX’s new hybrid system is so efficient it can drive at speeds below 40km/h for 2km on battery power alone -- providing the driver applies the throttle gently and the road is relatively flat.

The net result of all this technology means that the RX450h has a claimed fuel consumption average of 6.4L/100km. That’s less than a Toyota Yaris automatic.

However, the RX450h is no longer the most fuel-efficient mid-size luxury SUV, a title it held when it went on sale two years ago. The recently-released (and similarly-sized) BMW X3 2.0 diesel has a consumption average of 5.6L/100km and the BMW X3 3.0 diesel is rated at 6.0L/100km. The larger BMW X5 diesel uses 7.4L/100km.

Lexus’ hybrid is kinder to the environment, however. According to the Federal Government’s Green Vehicle Guide the RX450h has superior air pollution and greenhouse ratings than do its diesel-powered peers. The Lexus is also the only SUV in the GVG’s coveted Top 20 list.

And it still has diesel-like driving range; it can travel more than 1000km on one tank of petrol – in ideal driving conditions. That’s an important caveat. During our test we failed to get near the claimed 6.4L/100km average in a mix of city and highway driving. Our best consumption averages were closer to 8 or 9L/100km and up to 10 or 11L/100km at worst.

The model we tested was the top-line Sports Luxury with all the mod-cons. LED headlights (which follow the direction of the steering), side-view cameras, radar cruise control, heads-up display (which reflects the car’s speed in the windscreen in the driver’s line of sight), premium sound system, premium leather, 10-way adjustable driver’s seat, sunroof and 19-inch alloy wheels are some of the equipment highlights.

All RX models come with ten airbags: frontal airbags, knee protection, side airbags and ‘curtain’ airbags. Crash one and it will probably look like a jumping castle in there.

The RX’s body was shaped in a wind tunnel. A special undertray ensures smooth airflow under the body, and the side mirrors have been moved further away from the side glass to minimise wind noise. Lexus fitted felt lining under each wheelarch to prevent ‘road splash’ noises on wet roads.

The RX also debuted a new cabin control system for Lexus. The company’s answer to BMW’s iDrive (and the like), it uses haptic technology to allow the driver to ‘feel’ each subtle adjustment without having to take his or her eyes off the road.

The RX is a quiet achiever and driving it is almost a serene experience. The hybrid system is highly refined and the transition from petrol to electric power is almost seamless. As with most hybrid or electric cars, however, it still has an odd feel to initial brake pedal bite.

The Lexus may not have a performance car heritage behind it, but it’s still a competent all-rounder.

So when designing the new, second-generation Cayenne, Porsche had plenty of money to splash around on ways to cut the fuel bill (even though customers who can afford such an expensive 4WD can, presumably, afford to run it).

Porsche took to the new model with a guillotine, shedding up to 250kg from the previous model’s weight. The lightest in the new line-up, the Cayenne V6 petrol manual (a special order in Australia, all models are auto) sneaks under the two-tonne mark at 1995kg. An impressive effort…

This has been done by slashing 103kg from the body (using more aluminium panels), 74kg from the chassis (lighter suspension parts and smarter design), 63kg from the engine and transmission (including losing the low-range 4WD gearset) and 10kg from the electrical system (thinner wiring?). My favourite stat: 6kg was saved by switching to an electric park brake.

Note, however, the addition of more safety and luxury features has added 65kg worth of gear to the Cayenne that wasn’t there before.

All five models – the V6 petrol, V6 diesel, V6 hybrid, V8 petrol and V8 Turbo – come with automatic stop-start, so you’re not burning fuel while waiting at the traffic lights. And if you don’t like the judder when the engine returns to life, the system can be disabled at the press of a button.

All this has led to massive fuel saving across the new Cayenne range, by an average of 20 per cent. Alas in reality all this has done is brought the Porsche’s consumption back to the rest of the luxury 4WD field.

The headline act of the new range, the hybrid, is the heaviest of them all. It’s 240kg heavier than the regular V6 petrol, largely thanks to the electric motor and battery pack. It is also 125kg heavier than the Lexus RX hybrid, but the Cayenne is significantly bigger – and roomier – in every dimension.

At $160,800, the Cayenne S Hybrid is $55,000 dearer than the diesel, which also happens to be more efficient (8.2L/100km versus 7.4L/100km). Little wonder half of all Porsche Cayennes sold are the diesel model; no doubt the company is glad it revoked its pledge to never build one.

But, Porsche says, the Cayenne S Hybrid has V8 performance with V6 economy. And this is where the Lexus and Porsche hybrid SUVs begin to travel in different directions.

Porsche has favoured performance over economy. The numbers tell the story: the Lexus is considerably slower 0-100km/h than the Porsche (7.9 versus 6.5 seconds), but the Lexus is more fuel-efficient (according to the rating label).

In the real world, though the Cayenne is not much thirstier – if at all – than the Lexus hybrid. Our test achieved similar consumption numbers, of between 8 and 11L/100km.

We suspect the difference in the rating label numbers lies in the testing methods. The numbers you see on window stickers are derived from laboratory tests rather than real-world analysis.

As with the Lexus, the Porsche Cayenne S Hybrid can drive on electric power alone, petrol power alone or a combination of both. However, the Cayenne has only one electric motor nestled alongside the engine and gearbox, and it’s smaller and less powerful than either of the two electric motors in the Lexus.

Porsche says the Cayenne hybrid can drive up to 60km/h on battery power – in ideal conditions on a relatively flat road – but the smaller battery capacity means that it can only manage about 1km of petrol-free driving.

Instead, Porsche has focused on overtaking performance and quotes a 80-120km/h time of just 4.6 seconds. In comparison the V8 Cayenne does the same task in 4 seconds.

The Cayenne hybrid is a smooth operator but, oddly, the engine’s noisier than the diesel. On hard acceleration, the Audi-sourced supercharged V6 can be heard thrashing about more because the diesel has better sound-deadening.

The Hybrid drives well for a large 4WD, but it doesn’t corner as well as the other Cayenne models; you can really feel the extra weight.

And because the battery pack is under the rear floor, the space saver spare tyre (the size of a Labrador) sits upright in the cargo area, consuming valuable space. (In the Lexus, a full size spare tyre and carpeted cover is an extra $900 or $1000 depending on the model, and you lose only 10cm of depth in the load space).

Dynamically, both vehicles are competent. The Lexus has a smoother, quieter hybrid system and, in many regards, this makes it a more pleasant experience than the Porsche. The Cayenne hybrid is not as refined – or as quiet – as the Lexus and this particular model is also not the best execution of Porsche’s trademark handling.

We wouldn’t go as far to say that the Lexus drives better than the Porsche – but the RX450h does feel like a more complete, well-rounded package.

In reality if you want performance, economy and handling in a Porsche Cayenne, the $106,000 diesel is the way to go. If you crave a hybrid badge to please your peers, the Lexus mounts a strong argument.

Just please don’t ask us to choose between a Porsche Cayenne diesel and a Lexus RX450h at the same price. Because we’d probably pick the car that wasn’t even included in this test…

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