Lexus LS600h

What is it?

The LS600h is Lexus’s latest and undoubtedly greatest hybrid; it marries a 5.0-litre 388bhp V8 petrol engine with a 221bhp electric motor in what must be the most seamlessly integrated hybrid drivetrain yet created.

All in, the 600h packs 439bhp, and yet it pumps out just 219g/km of CO2; one gram below the far less powerful Mercedes S320 CDi. It’ll also do 0-62mph in 6.3sec and hit 155mph while returning an average 30.4mpg.

What’s it like?

At 60mph, the loudest noise in the LS600h isn’t the ticking of the clock. Neither is it the engine, road roar, or even wind noise.

No, the loudest noise comes from the electric fan of the air-conditioning unit, cooling the supremely comfortable soft leather seat upon which you are sitting. And even that’s hardly what you’d call loud.

But we already know that the LS is a supremely refined car; the V8-powered 460 offering a kind of hushed gentleman’s club luxury. So why bother with a hybrid version - after all, if you were really interested in saving the planet, would you really be wafting about in a massive luxury saloon?

Maybe not, but every little helps. And if you’re a captain of industry who needs to try to appear green but still has to be whisked from board meeting to airport without skipping a minute’s work, the LS is the only choice.

Green or not, the 600h is a seriously impressive device. Its V8 is a bored out version of the 460’s motor, but instead of that car’s eight-speed auto there’s a kind of continuously variable transmission in line with the electric motor. This is mated to a new Torsen diff that splits power front to rear.

Why the extra weight and complication of a four-wheel-drive system? Lexus reckons that this much power demands four-wheel drive.

The beautifully appointed cabin (the 600h only comes in one, top-level trim that includes a leather-covered dash) is familiar, as is the silence as you set off under electric power, but the combination of the two is quite something.

With over two tonnes to shift, the electric motor soon needs assistance. The switch in power is all but imperceptible, and acceleration comes in one seamlessly linear surge.

So refined is the LS that it’s easy to pick up excess speed. Should you enter a corner too briskly, it responds well, with less understeer than might be expected.

Body roll is well contained in the short-wheelbase car, which has highly effective active anti-roll bars, but your chauffeur won’t be able to get away with such tricks in the long-wheelbase machine, which isn’t so equipped.

Should I buy one?

Prices have yet to be confirmed ahead of the car going on sale in the UK in October 2007. It’s expected to start at £84,000. That’s a lot, but it’s also a lot less than an equivalently specced Merc.

Then again, you may need to add a chauffeur’s salary on top, for while it’s surprisingly engaging to drive, the best place to be is the back, especially if you get the long-wheelbase car with its optional individual ‘ottoman’ chairs.