WHEN Lexus announced it was introducing the RX270, a front-drive, four-cylinder petrol base variant for its luxury SUV range to sell alongside the well-established RX350 V6 and RX450h hybrid variants, we expected it to be a bit rubbish – but came away from our first drive impressed.

After all, naturally aspirated petrol engines lack torque compared with the turbo-diesel alternatives and are not best suited to big, heavy SUVs because they have to work that much harder to maintain momentum.

Four-cylinder engines can also get noisy, harsh and generally unrefined when working hard, and lugging a tall, wide, 1950kg SUV along is hard work for the new 2.7-litre engine, judging by its less-than-frugal official fuel consumption figure of 9.5 litres per 100 kilometres and the leisurely 11 seconds it takes to get from rest to 100km/h.

To fit a diesel was the obvious answer, but Lexus doesn’t do diesels – except for a couple of European-market models not sold in Australia – and if you want to save fuel it will point you in the direction of one of its hybrids, which also come with a handy slug of extra performance and are now more affordable than ever.

So, in the face of all the diesel conventional wisdom of Europe’s luxury SUV masters, we were pleasantly surprised by the entry-level RX270, which we drove back-to-back with the other new kid on the Lexus block, the RX450h in performance-oriented F-Sport specification.

The latter, thanks to price cuts across the RX range, is less expensive and more efficient than the Mercedes-Benz ML350 BlueTec and BMW X5 30d, while being similarly rapid.

Meanwhile, the RX270 is aimed to compete on price with smaller contenders like the Audi Q5 and BMW X3 while offering extra interior space.

As is the Lexus way, buyers of even the least expensive RX variant will hardly be left wanting for standard safety gear or luxury equipment, and technologies like sat-nav with SUNA traffic updates and DAB+ digital radio stand out from the crowd.

Higher-spec F-Sport and Sports Luxury variants get radar-based adaptive cruise control, and with that pre-collision warning with automatic emergency braking, but lane-keeping assistance and blind-spot monitoring are glaring omissions compared with new-generation contenders like the Mercedes-Benz M-Class.

We had reservations about how well the latest Lexus corporate face – first seen on the GS luxury sedan – would translate to the RX, but it is a successful transformation that brings its looks bang up to date.

On the other hand, the cabin will seem eerily familiar to owners of the outgoing model, with a dated-looking digital clock on the centre console and awful foot-operated parking brake.

However, as with the rest of the car, Lexus has applied subtle but numerous improvements that add up to more than the sum of their parts and we found the instruments informative, the controls intuitive and the general ambience of space, comfort and high quality materials for occupants front and rear.

All the useful storage areas are still there, such as the expandable hinged door bins, a large tray beneath the floating centre console and generous glove compartment, while the bin beneath the centre armrest now has a false floor that can be used to hide valuables or make it deep enough to accommodate an iPad or netbook.

Enhancements to body rigidity across the revised RX line-up – achieved through extra spot welds to the rear pillars and wheelarches, plus a reinforced dash panel – live up to the claims of improved handling and steering feel.

We were pleasantly surprised at how good the RX270 was to drive through Canberra and into the surrounding countryside, especially the direct, accurate and well-weighted steering operated through a good-to-grasp multi-function wheel.

The RX270’s brake pedal has a progressive action and plenty of feel, although the regenerative braking system of the RX450h numbed it somewhat, but not to the extent we were expecting, while both variants provided decent stopping power.

With 138kW of power and 252Nm of torque, the RX270 is not going to win any traffic-light grands prix, but its response from standstill or low speeds is pleasingly sharp, providing the confidence to duck into gaps on Canberra’s numerous roundabouts.

Lexus makes no bones about the RX270’s role as a city cruiser rather than back-road bruiser and the engine lacks the mid-range grunt to make for easy decision-making while contemplating how to get past a B-double on a country road.

Nor is it conducive to getting on the power when coming out of a tight turn, although shifting the six-speed automatic transmission’s selector to the Sport setting helps in the latter scenario by defaulting to a lower ratio and quickening the kick-down response to access the kiloWatts that hide in the upper rev range.

The RX270’s engine is eerily quiet and smooth, especially at idle and parking speeds, only making itself heard with a dreary drone when full-bore acceleration is asked of it.

Unavoidable SUV body shape-related acoustics were probably the cause of road noise levels on both variants being higher than expected, with the bigger 19-inch tyres of the RX450h contributing to more roar on coarse-chip bitumen.

There is much to like about the hybrid drivetrain of the RX450h, which provides levels of power, torque and fuel efficiency bettering a six-cylinder turbo-diesel with the free-revving character and linear power delivery of a naturally aspirated petrol engine plus the instant response of an electric motor that provides the opposite of turbo lag.

For us, the cruise control was a bugbear, being similar to the system fitted to the Australian-built Camry and Aurion sedans in that it will let the car run away with itself down hills rather than using the brakes or transmission to keep it to the set speed – and we even found this to happen on the adaptive system, which automatically brakes if a slower-moving vehicle in front is detected.

In addition, although all RX variants are fitted with hill-start assist, we found our RX450h rolling backwards down a hill while waiting to be allowed through some roadworks.

The RX270 is more softly sprung than the more powerful models and bumps are generally soaked up well for an SUV that corners so well – it hangs on doggedly to the chosen line and impresses with its lack of body-roll, while great forward visibility plus that accurate steering make it a cinch to place accurately on the road.

In this sense we consider the RX on a par with the Mercedes-Benz M-Class, but preferred the way the RX shrinks around the driver and never feels as big as it looks.

On the downside, rippled surfaces can overwhelm the suspension, causing things to get jiggly and more than once on our drive mid-corner bumps caused either the rear wheels to skip sideways or the steering rack to rattle – but even when pushing hard this was more of an annoyance than alarming.

For this reason, for us the BMW X5 maintains its position as the benchmark SUV for ride and handling as it takes poor road surfaces in its stride.

After admiring the RX270’s surprising nimbleness, we found the RX450h F-Sport can’t hide its extra 255kg of V6 engine, batteries and electric motors, despite the fitment of stiffer suspension, larger wheels and chassis flex-reducing ‘performance damper’ strut braces.

Although we have no complaints about its overall stability and roadholding, driving two-up the RX450h felt more cumbersome on corners, especially during quick direction changes or mid-corner steering adjustments, which would cause the car to pitch about uncomfortably, further distancing it from the holy grail of luxury SUV driving pleasure that is the X5.

Activating the new Sport mode gave the steering a new level of directness and weight, sharpened up the throttle response and injected a bit of extra punch from the electric motors, but overall we suspect the pick of the F-Sport bunch for driving enjoyment will probably be the less powerful, thirstier but 120kg lighter RX350, which runs a 204kW/346Nm V6 petrol engine.

We suspect that most people will buy an RX F-Sport for the looks and extra equipment than its dynamic abilities and any RX variant will provide enough of a car-like driving experience to satisfy the needs of most buyers while not completely frustrating the enthusiastic driver.

Lexus is not ruling out the addition of an F-Sport option for the currently single-spec RX270, which would be aimed at people who like the more aggressive body styling and funky dark chrome wheels, but its lack of engine performance might preclude it from the suspension upgrades.

We wouldn’t be surprised if, in addition to the new customers attracted by the RX270’s segment-busting price, existing RX350 owners traded down to the talented new base model, considering the increased specification and the number of small improvements that add up to make the RX a far better vehicle to drive and ride in than before.