Progression. It's a word which must haunt automotive engineers the world over. There's vast pressure for each subsequent generation of cars to be faster, smarter, safer and, increasingly, cleaner and meaner on fuel too. All of which means that as cars grow ever heavier and more powerful, engineers must pull the equivalent of a rabbit out of their hat and improve efficiency too. Such is the case with the latest Lexus RX350. The Japanese company have eked a reputation for working smarter rather than harder and the latest in their line of luxury 4x4s is evidence of this trend.

We've already seen the RX400h, a petrol electric hybrid model that offers the performance of a sports coupe with the fuel economy of a mid range saloon. The only problem was that it left the entry-level RX300 looking a bit like the class dunce. As Mercedes, BMW and Audi introduced plusher, more powerful 4x4s, the RX300 was, as James Brown once said, 'like a dull knife, not cutting.' The RX series hadn't always enjoyed the most savvy marketing. It was on sale in Japan as the Toyota Harrier for a couple of years before the penny dropped that it would sell in this country. For a couple of months it was the hot ticket before being thoroughly eclipsed by the introduction of the BMW X5. The UK isn't totally representative of the world market. The Lexus outsells its German rivals 3 to 1 in the USA, making it comfortably the world's biggest selling luxury 4x4. Now you can see why the RX is crucially important to Lexus' bottom line. The second generation models, of which the RX350 is one, freshened the appeal considerably and also positioned the RX as a mid-priced luxury 4x4, not attempting to duke it out with top end fare like Porsche Cayennes and Range Rovers.

"The RX350's engine is beautifully refined at typical motorway speeds"

It's a clever move because this is where much of the volume is. Take a look at the badges on the back of BMW X5 and Mercedes M Class models you see on the road and they'll likely be entry-level variants. These are the models Lexus is targeting with the RX350, a derivative that replaces the old RX300 with a bigger engine, better economy and a keener value proposition. The powerplant in question 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.

The RX350's engine is beautifully refined at typical motorway speeds although the big door mirrors create a reasonable amount of wind noise. When extended, the V6 engine responds with a rather tuneless turbine-like thrum that's rarely intrusive. The automatic gearbox slurs between ratios smoothly although it can be found wanting for drive when accelerating out of tight turns. In this instance, you'll probably prefer to knock the stick over into a tiptronic-style mode and change gear yourself between the five ratios. The steering has been revised to offer better feel at higher speed and more assistance at low speed but the helm is still probably the RX's least impressive feature. For a model that prides itself on its on-road handling and performance, the steering is not hugely confidence inspiring.

It's a rare albeit noticeable blip in an otherwise very capable car. The brakes are well up to the task and the cabin quality can only be described as brilliant. Even the entry level model never leaves you feeling shortchanged with features like electric seats, multi-zone air conditioning, cruise control, 17-inch alloy wheels and photochromic mirrors. This model opens proceedings at £32,035, but Lexus expects a good percentage of RX350 customers to opt for the SE model, priced at £36,185. This adds features such as electric seats with memory function and heating, leather trim, automatic lighting, electric rake and reach adjustment for the steering column, an electric sunroof, adaptive front lighting, 18-inch alloy wheels and the option of the Lexus Navigator satellite guidance system. The range-topping SE-L version is priced at £42,650 and has had most of the options list crowbarred in. Best of all is the Mark Levinson 11-speaker stereo that includes a six-disc DVD autochanger although the beautifully composed air suspension system runs it pretty close. The optional wood pack that slathers lumber on the dash and doors is probably best avoided.

Lexus reliability and after sales service we can take for granted but perhaps the RX's impressive safety credentials are occasionally overlooked. All models get twin front multi-stage airbags, curtain and front side bags as well as a driver's knee airbag. Anti-lock brakes with brakeforce distribution and brake assist are teamed with traction control and vehicle stability control to prevent a shunt in the first instance. Should the worst come to the worst, you not only have all that airbaggery but you also have seat belts with pretensioners, a retractable steering column and a collapsible pedal assembly. Impressive stuff. Other safety features standard on all variants include high intensity discharge headlights, LED tail lights, water repellent front door glass and front seats designed to combat the threat of whiplash.

Is it enough to punt the RX350 to the head of the class? On paper, yes. The trouble is, we rarely buy cars on a purely objective basis. As a nation, we're wedded to the premium German marques and will likely remain so for some time despite the best efforts of Lexus. If you can rise above vulgar badge snobbery, you'll find the RX350 has plenty to offer the independent thinker.

TOP 5 RX DEALS

The results below show the top RX deals on buyacar

	Lexus RX 400h 3.3 SE 5dr CVT Auto [Multimedia] Off Road
	ETR	Mthly	Saving £2,966	Price £39,679
	Lexus RX 400h 3.3 SR 5dr CVT Auto [Multimedia + ICE] Off Road
	ETR	Mthly	Saving £2,971	Price £39,734
	Lexus RX 400h 3.3 SR 5dr CVT Auto [Multimedia] Off Road
	ETR	Mthly	Saving £2,793	Price £37,712
	Lexus RX 400h 3.3 SR 5dr CVT Auto Off Road
	ETR	Mthly £636	Saving £2,555	Price £35,000
	Lexus RX 400h 3.3 SE-L 5dr CVT Auto Off Road
	ETR	Mthly £770	Saving £3,106	Price £41,269

typical 9.61% APR

PCP finance quote over 48 months,  10,000 miles pa,  deposit of £1000