I don't know about you but I struggle with the whole idea of taking a Lexus off road. It will be the same when Jaguar (inevitably) brings out one of these luxury 4x4s. You just can't get the core brand values out of your head and brand values for cars like these don't have much to do with mud. The last time I went over to the States, I noticed that Lexus dealers there were selling a rebadged version of Toyota's chunky, utilitarian-looking Land Cruiser Amazon. Now that would be a bit easier to take. But the latest Lexus RX350 I've been driving here looks so sporty, so suburbia that my local green laners would laugh themselves silly if I took it along to one of their mid-plugging meets. Having said all that, it's difficult not to covet this car. You can just see the envious glances down at Tesco and the commuters scuttling out of the way as you bear down on them in the fast lane.

I loved the sleek shape which gives the car a rather dynamic, futuristic look that appears a little smaller than the class norm. Despite this, we found the plush cabin to be pretty spacious, with plenty of room for two adults to spread out in the back on rear seats that can be slid back and forth to improve either legroom or the space on offer from the large boot. At the wheel, I found the driving position hard to fault, spoiled only by the great three-spoke sports steering wheel's lack of reach adjustment. I didn't like the centre console-mounted auto shift lever (there's no manual option of course) but in its defence, it frees up enough floor space for front passengers to walk through to the rear, should they need to separate warring back seat occupants. While we're on the autoshift, I was delighted to find it now operates five speeds, unlike its predecessor. Not that you should view the RX350 as any kind of sports saloon alternative. Throwing the car into a corner will only remind you that the carefully weighted power steering is still too light and encourage some frantic bleepings from the traction control and electronic stability systems (which you can't turn off). Not that it would ever occur to a typical Lexus customer to turn any kind of electronic safety programme off.

The powerplant stumps up with 272bhp which is enough to endow the RX350 with a reasonable turn of pace, getting it to 60mph in 7.8 seconds and on to a top speed of 124mph. A combined fuel economy figure of 25.2mpg is a reasonable return for such a quick, heavy vehicle, the old RX300 managing a figure of 23.2mpg. These figures make the Lexus the quickest and most economical sports utility in its class, eclipsing the likes of the Mercedes ML350, the BMW X5 3.0 auto and the Porsche Cayenne 3.2 on both counts. Like its saloon stablemates, this model is very good at ultimate comfort - which is why the Americans have bought it in such prodigious numbers. As in Lexus's flagship LS430 saloon, the engine is so quiet at idling speeds that I found myself having to look twice at the rev counter to remind myself that I'd really switched it on. Refinement from the outside world is almost as good - and would be even better were it not for those huge great door mirrors. There's not much else to criticise however, with even the door seals carefully designed for silence at high motorway speeds. Complaints about ride quality should also be few and far between: the RX350 is arguably almost class-leading in this respect. Ironically, this particular attribute makes the RX350 the ideal tool for what off roading it can manage. It simply sails over rutted fields and bumpy beaches, though the lack of serious essentials like a low ratio gearbox and a separate ladder frame chassis will prevent you from going too much further. That's why the standard specification doesn't include such irrelevancies as grab handles, compasses and tiltometers, What you do get is a full house stereo system, a trip computer, electric everything and those wonderful instruments that light up when you twist the key in the ignition. I did think however, that the shiny 'wood' detracted from the cabin's quality feel.

You can understand why the RX350 has been such a hit across the Atlantic in the market it was obviously designed for. It delivers, quite simply, what the shape and the badge promise: a Lexus luxury experience for those who want occasionally to venture slightly off the beaten track and need a more versatile alternative to a smart saloon. As a compromise choice for those undecided between a plush family 4x4 and a real luxury 4x4 model, it takes a lot of beating.