One and the same? Well, that's the funny thing - putting the Renault Koleos alongside the Nissan X-Trail raises no reasons for thinking they've been swimming in a common gene pool. Even after driving 'em, the picture's still no clearer.

This is badge-engineering 21st century style, and I'm all for it. To all technical intent, the Koleos is a Nissan X-Trail under the skin yet you'd be forgiven for not knowing this. The diesel versions that shared garage space for a week were remarkable in their lack of similarity.

Insofar as shared likeness goes, there's really nothing here you can actually see; even in the engine bay, the presentation is slightly different.

The styling? Well, the Renault's avantgarde approach is obviously from an entirely different school to Nissan's more staid preference. The interiors have no obvious compatibility save for some common fixture hardpoints and that they both seat five.

You might be forgiven for failing to twig that the drivetrains are inherently common; the 110kW/320Nm 2.0-litre diesel actually sounds less harsh on the move in the Renault (but noisier at idle). The French model also seems to hold longer in each of the (common) gearbox's cogs, though ultimately both deliver similar economy.

Competency-wise, they're generally much of a muchness, but here's something else. The X-Trail is essentially a front-drive model that either goes into four-wheel-drive as it feels necessary (in auto mode) or can be locked into all-paw action for low-speed running.

The Koleos does it the other way around, insofar that it's basically running in auto 4wd unless you make a conscious effort to click an adjuster switch to the 2wd zone. Option three, a 4wd 'lock' mode, works identically in each.

It's fair to start with the Frenchy because, whereas the Nissan is effectively an improvement of the first-gen original, the Koleos is all-new, not just as a car but also as a Renault.

The brand has never built anything quite like it before (though the best-forgotten Scenix RX4 did perform some similar functions) and it's the first model it has ever had with four-wheel drive offered at launch.

Koleos is a multi-national effort - Nissan chassis/platform and four-wheel drive technology, Renault engine and automatic gearbox put together in Pusan, Korea, by Samsung (Renault owns Nissan and a big chunk of Samsung) - but that's not why you'll remember it.

Using pre-existing bits makes logical sense in so many ways. And Renault should be getting a winning formula; the previous X-Trail was a strong seller, with more than 800,000 sold worldwide, and the new one largely addresses any weaknesses of the original recipe, while also maintaining the strengths.

Koleos is an important car for Renault NZ - it's expected to keep the cheques roiling in for a year until fresh passenger models land - but it's not going to do it easy, least of all now this sector is awash with choice.

The styling is original but quite vexing, the antitheses of the saying 'if it looks right, it probably is'. Though some aspects of the modern Renault look is evident, the shape as a whole is more angular and, er, quirkier than anything else this brand currently builds.

On the positive side, it's distinctive and a fresh departure from Nissan's box on wheels ethos. On the other hand it's not exactly cohesive or captivatingly handsome. The fastback that raises most comment also cripples cargo capacity; compared with the Scenic, which takes up similar roadspace, it's much less roomy in the rear.

Renault's seats are more comfy than Nissan's and Koleos is good at the small details (where's your auxiliary input, Nissan?) It's a pity the Scenic's clever seat-swappa arrangement cannot be replicated, but at least they've aced with the split tailgate. The bottom half is also up to taking significant weight.

In setup and style, the Koleos' instrument layout is pure Renault, notwithstanding that some of the buttons are in odd places. The shiny Korea-choice plastics are a poor example of Asian knock-off work by comparison with the Nissan's soft-touch choices.

The X-Trail's binnacle is as bluff as the exterior amd not as imaginative, but easy to navigate and there is some solid attention to detail within the cabin as a whole. There's 50 litres' storage space, including eight cup-holders, a lined dash-top box and various smaller bins, cubbies and boxes. The rear seat doesn't slide but is split 40:20:40 and the much-enlarged boot is more welcoming to xxl-boxes that might defeat the Koleos driver.

Equipment-wise, the Koleos does better with the final touches and on technology, with the novelty of a keycard starting system and an electronic hardbrake. But perceived value might did seem an issue with those who noted the X-Trail on test cost $2000 less than the $44,990 Koleos yet could offer leather and electric adjust seats to the Frenchie's cloth, DIY adjust items.

Safety-wise, at least, there's just no compromise with either. The Koleos is the 10th car Renault has produced that carries the maximum five-star Euro NCAP crash rating. It comes standard with ESP electronic stability/traction control, dual front, side and curtain airbags and three child seat anchor points for the rear seats. What's good enough for Renault is good enough for Nissan.

These cars aren't small Land Cruisers but they'll survive moderately challenging muddy, sandy and snowy bits and certainly won't have any trouble on the day care and primary school run.

The common 'intelligent' four-wheel drive system is reliable and it's handy to have hill hold assist and hill descent control (which even works in reverse). It's interesting that the Koleos is second-best for ground clearance - 188mm against 200mm - but has superior approach and departure angles, 27 and 31 degrees compared with 26 and 22.

The Koleos has the superior ride quality. Rutted gravel that had the X-Trail getting all bouncy left the Koleos much left ruffled. The downside to having such cosseting suspension is slightly more lean through the corners, but that's not an issue. The extra mass of a diesel engine is mainly felt in understeer.

The drivetrain is from Renault and is potentially the highlight whichever car you go to. Once up to open road pace, the diesel is working well. You're immediately aware that peak torque from the diesel is reached usefully lower in the rev range (2000rpm versus 4400rpm). Once the initial lethargy and gruffness is shaken off, it becomes muscular and sweet in responsiveness and sound. The six-speed auto is also an impressive accomplice - much better than the CVT Nissan hooks into its petrol mills - and the promise of 8.1 litres per 100km economy also attracts. The 'manual' function is rarely of much gain, except when tip-toeing down steep off-road sections.

It's usually fair to assume a diesel is the go for towing, so prepare to be perplexed. Usually, diesels outhaul petrols by some margin, yet this time the reverse is true, with both vehicles rated for just 1350kg against 2000kg braked for the petrol equivalents.

This is because the automatic lacks the transmission cooler meted the CVT model. That's a cruel blow, and needs sorting. Even so, the diesel-auto drivetrain is a big draw over the competition.

So, which to choose? As a former Scenic owner, I really wanted it to be the Koleos, but even sentiment can't sway it. In some ways it's the appearance, which depending on the angle swings between odd and awful. Mostly, though, it leaves the impression that it's just not quite as well sorted as it could, and should be.

The X-Trail could be better, too, particularly on the comfort side. Those flat seats really aren't good to sit in over a prolonged period. It's not as well-sorted within as the Koleos either, and frankly looks a bit dull at the kerbside, but overall is more practical and rather better finished.

It's a shame that it looks so much like the original but I'd find it easier to live with.

What this means to you: Koleos heads into new territory but X-Trail finds the spot.