Hybrid Lexus by name, but not nature

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Introduction

Lexus has been striving to distinguish itself in the luxury class for two decades and right now it has the only hybrid-powered car in the sector. The LS600h mates a 5.0-litre V8 petrol engine with an electric motor in a bid to deliver better economy and lower emissions to the world's elite. Does it work and is it enough to compete with turbodiesel rivals?

What are its rivals?

In the rarefied air of the luxury class, there are only a handful of competitors to the Lexus LS600h. The Mercedes S-Class in top spec diesel form is the key rival, delivering style, space and comfort attached to a reassuringly expensive badge. The new BMW 7 Series is the other main opponent to the Lexus, especially in 730d turbodiesel form with considerably better economy and emissions than the LS. Jaguar's XJ saloon, when powered by the 2.7-litre V6 turbodiesel, is a much more affordable option and stylish with it, though it doesn't quite have the gravitas or performance of the Lexus or its German rivals. Rounding off this slice of the sector is the Audi A8, which offers two turbodiesel options. The A8 is impressive on fuel consumption, but its ride comfort is not as good as its rivals' and that is a key consideration at this level.

How does it drive?

There's an eerie silence when you turn the key in the Lexus LS600h. To save fuel, the engine only fires at start-up if it is cold and the car needs a jolt of heat to get going. If the car's already warmed through, it will wake up but let the battery and electric motor take care of pulling away, so there's virtually no audible clue to the car's movement. Once rolling, the 5.0-litre V8 petrol engine kicks in seamlessly when the driver demands more acceleration, the speed exceeds 30mph or the battery begins to run low on juice. Whichever is the case, the petrol and electric motors work in harmony and, with 389bhp on tap from the V8 and a healthy dollop of oomph from the electric motor, acceleration is swift. Despite its 2,270kg heft, the LS600h will crack 0-62mph in 6.3 seconds and head on to an electronically governed top speed of 155mph. More relevant to LS600h customers, though, is the car's considerable comfort. The engine is always hushed and the continuously variable transmission (CVT), which shuns normal gears for bands that offer the best performance-to-economy balance possible, is flawless. Lexus has also long since worked out how to endow its largest saloons with suspension that simply refuses to acknowledge the presence of bumps and intrusions from the road's surface. So, all is calm inside the Lexus LS600h and that's great for the lucky few who get to travel in the rear seats. However, from the driver's pew, the steering has little in the way of feel and the LS doesn't have the same knack of moulding itself around the driver in the way a Mercedes or BMW does. Of course, it's not meant to be a sports car, but a little more driver interaction would be appreciated. On the upside, the Lexus is easy to slide through town streets thanks to a good turning circle and the reversing camera that shows up in a dash display makes parking oh-so simple.

What's impressive?

Refinement is the LS600h's forte, and this is a key attribute in this class and at this level. Close the door of the Lexus, soothe your way into one of its armchairs and the outside world melts away. Double-glazed door glass and huge amounts of sound proofing keep the world beyond the Lexus's cabin to a muted hum, even at fast motorway speeds. Road, wind and engine noise are banished and it's possible to hold a conversation with rear seat passengers at high speed without any need for the driver to raise his voice. Add in the Lexus's lengthy list of labour-saving and luxury-enhancing gadgets - such as heated and cooled leather seats, a superb CD stereo and touch-screen satnav - and the LS600h pampers like a weekend away at a spa resort.

What's not?

Given the raison d'être behind the Lexus LS600h is economy improvement and emissions reduction, its 30.4mpg combined consumption and 219g/km are not so good. It may be impressive for a petrol engined car of this size and capacity, but several of the LS's diesel-powered rivals are cleaner and more frugal, and they have lengthier service intervals than the Lexus's 10,000-mile schedule. Then there's the cost of choosing the Lexus over its obvious diesel rivals. With a list price of more than £80,000, the LS600h comes in at around £20,000 more than a lavishly equipped diesel version of the Audi A8, BMW 7 Series or Mercedes S Class.

Should I buy one?

If you want one of the ultimate luxury saloons on the market, the Lexus LS600h should be on your 'to try' list. It offers faultless build quality and the full gamut of toys and comfort aids, but then so it should for the considerable price. Therein lies the problem with the LS600h: it's much more expensive than rivals that boast better economy and emissions. Consider the Lexus as a rival to the top of the range V12-powered luxo-limos and it's on a more even footing, but then these petrol cars sell in such tiny numbers that Lexus needn't have bothered with the hybrid power plant. To answer our questions at the beginning: yes, it works, but no, it's not enough for Lexus to gain any more ground in such exalted company.

Alisdair Suttie