Summing up a car whose handbook contains nearly 700 pages isn't easy, but here goes: the LS 600h L is the finest example of the kind of car Lexus does best. While other models seem to me to fall short of excellence in various ways, this one justifies the brand's existence all on its own.Regular readers will know that I tested an LS 460 a while ago and wasn't fully impressed by it. That car's bigger brother is superior in almost every way. It's faster, it's more comfortable, and it even has significantly better fuel economy. It's also staggeringly more expensive, but I suppose you can't have everything.Under the bonnet (and hidden under a plastic cover as if to suggest that Lexus clients ought not to be troubled by such things) lies a five-litre V8 petrol engine. That's one of the power units, the other being an electric motor which sometimes helps the engine along and sometimes replaces it altogether. Their combined effect is to provide a maximum of 439bhp, which is rather a lot; you have to press a special button on a BMW M5 to make it produce more than that.Straightline performance is quite something. Floor the throttle and this very large machine hurtles towards the horizon in a very surprising manner - 0-62mph in 6.3 seconds doesn't tell you everything, but it should give you a good idea of just how quick this thing is. Even more surprising is the combined fuel economy, which is just on the angels' side of 30mpg, or the same as a Ford Focus ST. This means that the LS 600h is a lot cheaper to run that it looks like it should be, and with CO2 emissions of 219g/km it's relatively cheap to tax as well.This is all thanks to the hybrid powertrain, of course, but it occurs to me that saving a few hundred quid a year on tax and fuel bills, appealing as this undoubtedly is, can't be the main reason for buying the car. I mean, the "basic" LS 600h costs £81,410, the long-wheelbase one costs £83,655, and if you want the long-wheelbase model with the optional Rear Seat Relaxation Pack as tested here (and believe me you do, as I'll explain later), you're going to have to write a cheque for no less than £88,000. If you can afford that, why would you devote any consideration to the fact that it's a hybrid?Well, it's like this. With most other hybrids, the improved fuel economy is what matters, but in the case of the LS 600h I don't believe that's the case. What the hybrid technology does here is enhance the sense of luxury. There's a big V8 under the bonnet, and it's ready to spring into action as soon as you need to use it. But if you don't need to use it, it switches itself off and sits silently awaiting your call. Can you imagine what a sense of power that gives to the driver? I bet you're having to swallow a sudden overdose of saliva at the very thought.Running on electric power only, the LS 600h is almost completely silent, but it's like that most of the time anyway. In gentle - perhaps I should say "serene" - motoring you can only tell whether the engine is running by looking at the revcounter. The transition from engine-off to engine-on is so Jeeves-like that you can barely hear or feel it, especially if you're having a conversation or listening to the excellent Mark Levinson 19-speaker audio system at the time.Of course it's whisperingly quiet from the outside too, and if you're going slowly in a built-up are it's best to keep an eye on the pedestrians and not assume that they can hear you coming. Unless they can see the car, the only warning they're going to get is the swish of the tyres.The tyres. Mm-hmm. The LS 600h uses 45-section rubber, and I'm not convinced that this is a good idea. They pick up quite a lot of road noise, and they make the otherwise excellent ride fussier than I think it should be. Smaller wheels and larger sidewalls would be more in keeping with the feel of the car, though having said that I should add that the ride is nevertheless better than it is on the LS 460, possibly because the 600 is appreciably heavier.And the tyres do provide a lot of grip, which means you can get through corners at a fair old rate even though this is by no means a sporting car. It's far too heavy for that, though the weight is fully apparent only during urgent braking or over-adventurous entry to corners. A switch on the centre console offers Comfort and Sport modes on either side of the standard damper setting, and although the differences in behaviour are slight they are sufficient to make it worthwhile swapping among them as road conditions change.Apart from that slightly jittery ride, comfort levels are very high. The seats are excellent, the steering wheel can be altered just so, and the attractive dash and light-coloured leather are pleasing to the eye. The only real jarring note is the wood-effect plastic trim, which knocks several thousand pounds off the perceived value of the car; it also covers the part of the steering wheel you're most likely to hold on to, and is quite slippery, so you wouldn't want to drive this thing with sweaty palms.As you'll have noticed, most of what I've written so far has been from the driver's point of view, but to be honest the best seat in the house - if you've done the proper thing and opted for the Relaxation Pack mentioned earlier - is the one diagonally opposite where the driver sits.From here, at the touch of a button, you can move the front passenger seat as far forward as it will go, recline to a suitable angle, load a DVD (through a system which also includes a roof-mounted 9" screen and is part of the standard equipment) and choose one of four available massage programmes, each with their own speed and intensity settings, to which you can add a vibration function which is also adjustable.As a conscientious journalist I realised that it would have been a disservice to my readers not to try this out. So there I sat, reclined to just the extent I wanted, watching excerpts from Fiddler On The Roof (including - and I didn't appreciate the irony until several hours later - the bit where Topol sings "If I Were A Rich Man"), having all manner of stress and tension squeezed from my muscles, and thinking that I would have no problem getting used to this; and then, extending the thought a little further, realising that I could quite happily spend a whole day like this as my chauffeur whisked us down the autoroutes to a late dinner in Monte Carlo.I must try that some time. Engine 4969 cc, 8 cylinders Power 439 bhp @6400 rpm Torque 384 ib/ft @4000 rpm Transmission 8 speed semi-auto Fuel/CO2 30.4 mpg / 219 g/km Acceleration 0-62mph: 6.3sec Top speed 155 mph Price From £90280.00 approx Release date 01/10/2007